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1999-2005 Audi A2 SUV General information on refrigerant circuit User Manual

MY CAR USER MANUAL

General information on refrigerant circuit for Your Audi A2 SUV 1999-2005

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3
General information on refrigerant  
circuit  
Vehicles with high-voltage system (hybrid vehicles)  
High voltage! Danger to life!  
The voltage levels in the high-voltage system constitute a safety  
hazard. Danger of severe or fatal injuries from electric shock.  
– Persons with life-sustaining or other electronic medical devi‐  
ces in or on their body must not perform any work on the high-  
voltage system. Such medical devices include internal anal‐  
gesic pumps, implanted defibrillators, pacemakers, insulin  
pumps and hearing aids.  
– The high-voltage system must be de-energised by a suitably  
qualified person.  
Risk of injury - engine may start unexpectedly  
It is difficult to determine whether the drive system of an electric  
vehicle or hybrid vehicle is active. Moving parts can trap or draw  
in parts of the body.  
– Switch off ignition.  
– Place ignition key outside vehicle.  
Risk of damage to high-voltage wiring  
Incorrect handling may result in damage to the insulation of high-  
voltage wires or high-voltage connectors.  
– Never use high-voltage wiring or high-voltage connectors as  
a support.  
– Never prop tools against high-voltage wiring or high-voltage  
connectors.  
– Never bend or kink high-voltage wiring.  
– Pay attention to coding when connecting high-voltage con‐  
nections.  
♦ For all work on vehicles with high-voltage system, note addi‐  
tional warnings for working on such vehicles  
⇒ “1 Warning instructions when working on vehicles with high-  
voltage system”, page 1 .  
♦ If work near high-voltage system components is necessary,  
perform a visual check of the high-voltage components and  
wires to check for damage ⇒ page 2 .  
♦ If work on high-voltage system components is necessary, de-  
energise high-voltage system ⇒ Rep. gr. 93 ; De-energising  
high-voltage system or ⇒ Electrical system; Rep. gr. 93 ; De-  
energising high-voltage system .  
28  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Vehicles with start/stop system  
Risk of injury - engine may start unexpectedly  
The engine can start unexpectedly if the vehicle's start/stop sys‐  
tem is activated. A message in the instrument cluster indicates  
whether the start/stop system is activated.  
– To deactivate the start/stop system, switch off the ignition.  
All vehicles  
⇒ “3.1 Components of refrigerant circuit”, page 29  
⇒ “3.2 Layout of components of refrigerant circuit and their influ‐  
ence on high-pressure and low-pressure sides”, page 30  
⇒ “3.3 Design of refrigerant circuit”, page 48  
⇒ “3.5 Connections for quick-release coupling in refrigerant cir‐  
cuit”, page 51  
⇒ “3.6 Switches and senders in refrigerant circuit and related  
connections ”, page 57  
⇒ “3.7 Electrical components not installed in refrigerant circuit”,  
page 65  
⇒ “3.8 Pressures and temperatures in refrigerant circuit”,  
page 65  
⇒ “3.9 Tests and measurements performed with pressure gauge”,  
page 70  
⇒ “3.10 Air conditioner service and recycling units”, page 71  
⇒ “3.11 Repair notes for refrigerant circuit”, page 72  
3.1  
Components of refrigerant circuit  
Caution  
Tools or materials (e.g. sealing additives) that have not been  
approved can damage or impair the system.  
Use only tools and materials that have been approved by the  
manufacturer.  
Warranty claims are not accepted if tools or materials that have  
not been approved are used.  
•
•
All components of the refrigerant circuit submitted for quality  
analysis should always be sealed (use original sealing caps of  
replacement part).  
Renew damaged or leaking components of refrigerant circuit  
⇒ page 272 .  
Note  
The following replacement parts were previously filled with nitro‐  
gen gas: air conditioner compressor, reservoir, evaporator and  
condenser. This charge is being gradually discontinued. There‐  
fore, little or no pressure equalisation can be perceived when the  
sealing plugs of the replacement part are unscrewed.  
3. General information on refrigerant circuit  
29  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.2  
Layout of components of refrigerant cir‐  
cuit and their influence on high-pressure  
and low-pressure sides  
High-pressure side: Condenser, receiver and restrictor or expan‐  
sion valve to separate the high and low-pressure liquid ends.  
High pressure results from the restrictor or expansion valve form‐  
ing a constriction and causing the refrigerant to build up, thus  
leading to an increase in pressure and temperature.  
Excess pressure occurs if too much refrigerant or refrigerant oil  
is used, the condenser is contaminated, the radiator fan is defec‐  
tive, the system is blocked or in the event of moisture in the  
refrigerant circuit (icing-up of restrictor or expansion valve).  
Low-pressure side: Evaporator, evaporator temperature sensor  
and air conditioner compressor to separate the sections with high  
and low gas pressure.  
A drop in system pressure can be caused by a loss of refrigerant,  
the restrictor or expansion valve (constrictions), a defective air  
conditioner compressor or an iced-up evaporator.  
30  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
⇒ “3.2.1 Mechanically driven air conditioner compressor”,  
page 31  
⇒ “3.2.2 Electrically driven air conditioner compressor for vehicles  
with a high-voltage system”, page 32  
⇒ “3.2.3 Condenser”, page 36  
⇒ “3.2.4 Evaporator”, page 36  
⇒ “3.2.5 Heat exchanger for heat pump operation”, page 37  
⇒ “3.2.6 Fluid collector”, page 37  
⇒ “3.2.7 Reservoir”, page 38  
⇒ “3.2.8 Restrictor”, page 38  
⇒ “3.2.9 Receiver”, page 40  
⇒ “3.2.10 Expansion valve”, page 41  
⇒ “3.2.11 Expansion valve with shut-off valve”, page 41  
⇒ “3.2.12 Refrigerant shut-off valves”, page 42  
⇒ “3.2.13 Refrigerant line with internal heat exchanger”,  
page 44  
⇒ “3.2.14 Quick-release couplings on refrigerant line”,  
page 44  
⇒ “3.2.15 O-rings”, page 46  
⇒ “3.2.16 Pipes and hoses of refrigerant circuit”, page 46  
⇒ “3.2.17 High-pressure safety valve”, page 46  
⇒ “3.2.18 Non-return valves”, page 47  
3.2.1  
Mechanically driven air conditioner com‐  
pressor  
The air conditioner compressor is driven by the engine via a poly  
V-belt or a drive shaft.  
Air conditioner compressor with magnetic clutch:  
♦ An electromagnetic clutch -A- attached to the air conditioner  
compressor provides the power link between the pulley -B-  
and the compressor crankshaft when the air conditioning is  
switched on.  
♦ An overload protection attached to the clutch plate or fitted in  
the solenoid of the air conditioner compressor is triggered if  
the air conditioner compressor is not running smoothly in order  
to protect the belt drive against overload.  
Air conditioner compressor with no magnetic clutch:  
♦ An overload protection attached to the pulley -B- or fitted in the  
drive unit of the air conditioner compressor is triggered if the  
air conditioner compressor is not running smoothly in order to  
protect the belt drive against overload.  
All air conditioner compressors  
The air conditioner compressor draws in refrigerant gas from the  
evaporator, compresses it and conveys it to the condenser.  
3. General information on refrigerant circuit  
31  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Note  
♦ The air conditioner compressor contains refrigerant oil which  
mixes with refrigerant R134a at all temperatures.  
♦ The type plate indicates the refrigerant for which the air con‐  
ditioner compressor is designed. A valve regulates the pres‐  
sure on the low-pressure side within the specified range  
(control characteristic).  
♦ At present, actuation is effected externally by way of a regu‐  
lating valve -C- on air conditioner compressors with or without  
magnetic clutch.  
♦ On air conditioner compressors with no magnetic clutch, the  
engine is only to be started following complete assembly of the  
refrigerant circuit.  
♦ To prevent air conditioner compressor damage if the refriger‐  
ant circuit is empty, the magnetic clutch is deactivated and the  
air conditioner compressor regulating valve - N280- no longer  
actuated (air conditioner compressor idles with engine).  
♦ If the refrigerant circuit is empty, an air conditioner compressor  
with no air conditioning system magnetic clutch - N25- (with  
air conditioner compressor regulating valve - N280- ) is switch‐  
ed to internal lubrication by way of a valve.  
♦ Depending on the version of the air conditioner compressor,  
there may be a valve on the high-pressure side of the com‐  
pressor which prevents liquid refrigerant from flowing back into  
the compressor after the air conditioner has been switched off.  
If an air conditioner compressor with such a valve is installed  
in a vehicle with a refrigerant circuit with an expansion valve,  
it may take a relatively long time before the pressure in the  
high-pressure side drops (the expansion valve is cold and the  
pressure in the low-pressure side increases rapidly after the  
compressor is switched off; the expansion valve is closed and  
the refrigerant can only flow slowly to the low-pressure side).  
If the air conditioner compressor is switched on, the pressure  
in the low-pressure side drops, the expansion valve is opened  
and the refrigerant can flow to the low-pressure side.  
♦ On air conditioner compressors with an electromagnetic clutch  
-A- and a regulating valve -C-, the electromagnetic clutch -A-  
is usually only activated in conjunction with regulating valve  
-C- ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant cir‐  
cuit .  
3.2.2  
Electrically driven air conditioner com‐  
pressor for vehicles with a high-voltage  
system  
Vehicles with high-voltage system (hybrid vehicles)  
High voltage! Danger to life!  
The voltage levels in the high-voltage system constitute a safety  
hazard. Danger of severe or fatal injuries from electric shock.  
– Persons with life-sustaining or other electronic medical devi‐  
ces in or on their body must not perform any work on the high-  
voltage system. Such medical devices include internal anal‐  
gesic pumps, implanted defibrillators, pacemakers, insulin  
pumps and hearing aids.  
– The high-voltage system must be de-energised by a suitably  
qualified person.  
32  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Risk of injury - engine may start unexpectedly  
It is difficult to determine whether the drive system of an electric  
vehicle or hybrid vehicle is active. Moving parts can trap or draw  
in parts of the body.  
– Switch off ignition.  
– Place ignition key outside vehicle.  
Risk of damage to high-voltage wiring  
Incorrect handling may result in damage to the insulation of high-  
voltage wires or high-voltage connectors.  
– Never use high-voltage wiring or high-voltage connectors as  
a support.  
– Never prop tools against high-voltage wiring or high-voltage  
connectors.  
– Never bend or kink high-voltage wiring.  
– Pay attention to coding when connecting high-voltage con‐  
nections.  
♦ For all work on vehicles with high-voltage system, note addi‐  
tional warnings for working on such vehicles  
⇒ “1 Warning instructions when working on vehicles with high-  
voltage system”, page 1 .  
♦ If work near high-voltage system components is necessary,  
perform a visual check of the high-voltage components and  
wires to check for damage ⇒ page 2 .  
♦ If work on high-voltage system components is necessary, de-  
energise high-voltage system ⇒ Rep. gr. 93 ; De-energising  
high-voltage system or ⇒ Electrical system; Rep. gr. 93 ; De-  
energising high-voltage system .  
– To minimise the number of automatic engine starts when the  
vehicle's drive system is active during test and measurement  
work, charge the vehicle batteries e.g. with the battery  
charger 60A - VAS 5904- in battery standby mode ⇒ Electrical  
system; General information; Rep. gr. 27 ; Charging battery  
and ⇒ Electrical system; Rep. gr. 93 ; General warning in‐  
structions for work on the high-voltage system .  
3. General information on refrigerant circuit  
33  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
– For test and measurement work that requires the vehicle's  
drive system to be active (READY) or the ignition to be switch‐  
ed on, move the selector lever to position “P”, activate the  
parking brake and take care to keep well clear of the engine  
when it is running. Set up any tools needed so that they cannot  
come into contact with moving parts.  
Electrically driven air conditioner compressor  
WARNING  
Danger of short circuit  
The air conditioner compressor operates at up to 288 V in a  
speed range between 800 and 8600 rpm.  
Avoid contact with the air conditioner compressor when switch‐  
ing on the ignition or starting the drive units - danger of short  
circuit.  
♦ The air conditioner compressor draws in refrigerant gas from  
the evaporator, compresses it and conveys it to the condens‐  
er.  
♦ The electric motor of the air conditioner compressor is sup‐  
plied with power by the power and control electronics for  
electric drive - JX1- .  
♦ The control unit for air conditioning compressor - J842- inte‐  
grated in the air conditioner compressor regulates the speed  
and thereby the output of the air conditioner compressor ( elec‐  
trical air conditioner compressor - V470- ) based on the re‐  
quest received via the data bus ⇒ Vehicle diagnostic tester,  
“Guided Fault Finding” function for air conditioner and battery  
regulation .  
♦ The electrically driven air conditioner compressor is not fitted  
with an air conditioner compressor regulating valve - N280- .  
♦ Prior to installation, check the air conditioner compressor and  
bracket attachment points. The contact surfaces must be  
clean and free from rust and grease. If this is not the case,  
treat the contact surfaces accordingly with the contact surface  
cleaning set - VAS 6410- ⇒ Electrical system; General infor‐  
mation; Rep. gr. 97 ; Repairing wiring harnesses and con‐  
nectors .  
34  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Note  
♦ If the control unit for air conditioning compressor - J842- is  
defective, the amount of refrigerant oil in the new air condi‐  
tioner compressor must be adjusted. The refrigerant circuit  
does not have to be flushed with R134a.  
♦ The control unit for air conditioning compressor - J842- and  
the electrical air conditioner compressor - V470- form one  
component and cannot be separated at present.  
♦ The electrically driven air conditioner compressor is not fitted  
with -N280- . The output of the air conditioner compressor is  
regulated externally by way of the air conditioner compressor  
speed ⇒ Current flow diagrams, Electrical fault finding and Fit‐  
ting locations and ⇒ Vehicle diagnostic tester, “Guided Fault  
Finding” function for air conditioner and battery regulation .  
♦ At present, the electrically driven air conditioner compressor  
operates on the principle of a scroll-type supercharger (similar  
to the "G-Lader" supercharger).  
♦ The air conditioner compressor contains refrigerant oil which  
mixes with refrigerant R134a at all temperatures.  
♦ The type plate indicates the refrigerant for which the air con‐  
ditioner compressor is designed.  
♦ The integrated electronics regulate the output of the air con‐  
ditioner compressor (and thus the pressure on the low-pres‐  
sure side) within the specified range (control characteristic) by  
way of the speed.  
♦ The engine should only be started after the refrigerant circuit  
has been assembled completely.  
♦ The air conditioner compressor is fitted with a secured oil sup‐  
ply to prevent damage if the refrigerant circuit is empty. This  
3
means that approx. 40 to 50 cm of refrigerant oil remains in  
the air conditioner compressor.  
♦ Like the mechanically driven air conditioner compressor, the  
electrically driven air conditioner compressor has a pressure  
relief valve.  
♦ On vehicles with battery cooling, hybrid operation is only pos‐  
sible with the air conditioner charged and with no air condi‐  
tioner faults stored ⇒ Vehicle diagnostic tester, “Guided Fault  
Finding” function for air conditioner and battery regulation .  
♦ After installing the electrically driven air conditioner compres‐  
sor and then charging the refrigerant circuit, first start up the  
compressor via the “Compressor run-in” function of the basic  
setting routine. Otherwise, the air conditioner compressor may  
be damaged if refrigerant oil has accumulated in the compres‐  
sion chamber of the air conditioner compressor due to inap‐  
propriate storage prior to installation ⇒ Vehicle diagnostic  
tester in “Guided Fault Finding” mode for air conditioner and  
battery regulation .  
♦ An electrically driven air conditioner compressor may only be  
activated when the refrigerant circuit is charged. Running the  
air conditioner compressor with the refrigerant circuit empty  
could lead to compressor damage ⇒ Vehicle diagnostic tester  
(“Guided Fault Finding” mode for air conditioner and battery  
regulation) .  
3. General information on refrigerant circuit  
35  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.2.3  
Condenser  
The condenser transfers heat from the compressed refrigerant  
gas to the surrounding air.  
When this happens, the refrigerant gas condenses to liquid.  
Note  
♦ Depending on the design of the refrigerant circuit, the receiver  
may be attached to the condenser or integrated in the con‐  
denser ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant  
circuit (vehicle-specific Workshop Manual) and ⇒ Electronic  
parts catalogue .  
♦ There are different versions of the condenser; from the outside  
these versions can only be identified by their part number.  
Version -1- of the condenser is split into two sections (“two-  
pass condenser”). Version -2- of the condenser is split into four  
sections (“four-pass condenser”).  
♦ This illustration shows a condenser with the receiver -C- at‐  
tached.  
♦ The gaseous refrigerant enters the condenser at connection  
-A-; the refrigerant is then cooled down in the condenser and  
turns into liquid.  
♦ The liquid refrigerant accumulates in receiver -C- (with dryer)  
and flows through the bottom cooling section to connection  
-B-.  
♦ The refrigerant capacity in a refrigerant circuit may differ de‐  
pending on the design of the condenser (internal volume, flow,  
etc.). Therefore always pay attention to the correct version and  
allocation of the condenser ⇒ page 292 and ⇒ Electronic  
parts catalogue .  
3.2.4  
Evaporator  
Evaporators come in different versions. Depending on the layout  
and function, the thermal energy required to evaporate the refrig‐  
erant is taken from the air flowing through the evaporator (e.g. in  
the case of the evaporator in the air conditioning unit or in the  
battery cooling module) or the coolant flowing through the evap‐  
orator (e.g. in the case of the heat exchanger for high-voltage  
battery) ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant  
circuit (vehicle-specific Workshop Manual).  
Note  
Two evaporator versions are described below.  
36  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Evaporator in the air conditioning unit (or in the battery cooling  
module)  
The liquid refrigerant evaporates in the tubes of the evaporator.  
The heat required for this is extracted from the air flowing past the  
evaporator fins. The air cools down. The refrigerant evaporates  
and is extracted from the air conditioner compressor with the ab‐  
sorbed heat.  
A defined quantity of refrigerant is supplied to the evaporator by  
way of a restrictor or expansion valve. In systems with an expan‐  
sion valve, the flow rate is regulated so that only gaseous refrig‐  
erant emerges at the evaporator outlet.  
Evaporator/heat exchanger for high-voltage battery (chiller)  
The liquid refrigerant evaporates in the evaporator (heat ex‐  
changer). The heat required for this is extracted from the coolant  
flowing through the evaporator. The coolant cools off, and the re‐  
frigerant evaporates and is drawn in by the air conditioner com‐  
pressor with the absorbed heat.  
A specified quantity of refrigerant is supplied to the evaporator via  
a restrictor (or an expansion valve) and a shut-off valve. The flow  
rate of the refrigerant (or coolant) is regulated so that the refrig‐  
erant emerging from the evaporator outlet is in gaseous form only  
⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (ve‐  
hicle-specific Workshop Manual).  
3.2.5  
Heat exchanger for heat pump opera‐  
tion  
The refrigerant (gaseous or vaporous) compressed by the air  
conditioner compressor is liquefied in the heat exchanger -A-; the  
released heat is transferred to the coolant flowing through ⇒  
Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-  
specific Workshop Manual).  
3.2.6  
Fluid collector  
In certain operating modes (e.g. in heat pump mode), the receiver  
(e.g. on the condenser). is not incorporated in the refrigerant cir‐  
cuit. The fluid collector -B- collects the refrigerant, stores a certain  
amount of it (if not required) and then transfers it as a continuous  
flow to the expansion valve (in front of the evaporator in the heater  
and air conditioning unit) or to the heat exchanger in the high-  
voltage system's coolant circuit ⇒ Heating, air conditioning; Rep.  
gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).  
3. General information on refrigerant circuit  
37  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.2.7  
Reservoir  
The reservoir collects the vapour and gas mixture coming from  
the evaporator to ensure that the air conditioner compressor only  
receives gaseous refrigerant. The vapour turns into gaseous re‐  
frigerant.  
Refrigerant oil entrained in the circuit does not remain in the res‐  
ervoir as there is an oil extraction hole.  
Any moisture which enters the refrigerant circuit during assembly  
is trapped by a filter (desiccant bag) in the reservoir.  
Gaseous refrigerant with oil is drawn in by the air conditioner  
compressor.  
Note  
♦ Renew reservoir if refrigerant circuit has been open for a rel‐  
atively long period and moisture has entered, or if renewal is  
stipulated due to a specific complaint ⇒ page 272 .  
♦ Do not remove sealing plugs -A- and -B- until immediately prior  
to installation.  
♦ If a reservoir is not sealed, the desiccant bag soon becomes  
saturated with moisture and can no longer be used.  
♦ When installing, observe arrow indicating direction of flow (if  
applicable).  
3.2.8  
Restrictor  
Restrictor upstream of evaporator  
The restrictor creates a constriction. The restriction restricts the  
flow, thus separating the refrigerant circuit into high and low-pres‐  
sure sides. Upstream of the restrictor, the refrigerant is warm due  
to the high pressure. Downstream of the restrictor, the refrigerant  
is cold due to the low pressure. A strainer is fitted upstream of the  
constriction to trap dirt. The strainer downstream of the constric‐  
tion is designed to atomise the refrigerant before it enters the  
evaporator.  
Note  
♦ Arrow -A- on restrictor faces evaporator.  
♦ Always renew after opening circuit.  
♦ There are different versions; observe the notes in the service  
information media available ⇒ Heating, air conditioning; Rep.  
gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual)  
and ⇒ Electronic parts catalogue .  
Restrictor upstream of heat exchanger for high-voltage battery  
(chiller)  
38  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
The restrictor creates a restriction, which restricts the flow, thus  
separating the refrigerant circuit into high and low-pressure sides.  
Upstream of the restrictor, the refrigerant is warm due to the high  
pressure. Downstream of the restrictor, the refrigerant is cold due  
to the low pressure.  
Note  
♦ The illustration shows a refrigerant line -A- with a permanently  
installed restrictor -B- (without strainer).  
♦ The diameter of the restrictor hole -B- is approx. 0.7 mm. De‐  
pending on the version of the refrigerant line, the restrictor is  
either only inserted or fixed in position in the refrigerant line. If  
it is inserted, there may be a strainer for separating float ele‐  
ments, which may block off the restrictor hole.  
♦ Prior to installation, check for dirt, and clean or renew the  
component as necessary.  
♦ There are different versions; observe the notes in the service  
information media available ⇒ Heating, air conditioning; Rep.  
gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual)  
and ⇒ Electronic parts catalogue .  
3. General information on refrigerant circuit  
39  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.2.9  
Receiver  
The receiver collects the droplets of liquid and conveys them in a  
continuous stream to the expansion valve. Any moisture ingress‐  
ing into the refrigerant circuit during assembly is collected by a  
dryer in the receiver.  
Note  
♦ Renew receiver if refrigerant circuit has been open for a rela‐  
tively long period and moisture has entered, or if renewal is  
stipulated due to a specific complaint ⇒ page 272 .  
♦ Do not remove sealing plugs until just before installation.  
♦ If the receiver is not sealed, the desiccant bag soon becomes  
saturated with moisture and thus unusable.  
♦ When installing, observe arrow indicating direction of flow (if  
applicable).  
♦ Depending on the design of the refrigerant circuit, the receiver  
may also be attached to the condenser or integrated in the  
condenser ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrig‐  
erant circuit (vehicle-specific Workshop Manual) and ⇒ Elec‐  
tronic parts catalogue .  
♦ The procedure for dealing with problems differs depending on  
the version of the receiver / desiccant cartridge. If, for example,  
the receiver is attached to the condenser, it can be renewed  
together with the desiccant cartridge. If, for example, the re‐  
ceiver is integrated into the condenser, it is usually possible to  
renew the desiccant cartridge and any additional filter element  
separately. If the receiver is integrated into the condenser and  
it is not possible to renew the receiver/desiccant cartridge  
separately, it may be necessary to renew the entire condenser  
⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit  
(vehicle-specific Workshop Manual) and ⇒ Electronic parts  
catalogue .  
♦ Depending on the design of the refrigerant circuit, the desic‐  
cant bag (desiccant cartridge) may also be installed in the  
condenser ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrig‐  
erant circuit (vehicle-specific Workshop Manual) and ⇒ Elec‐  
tronic parts catalogue .  
40  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.2.10  
Expansion valve  
The expansion valve atomises the refrigerant flowing in and con‐  
trols the flow rate according to the heat transfer so that it does not  
vaporise before reaching the evaporator outlet.  
Note  
♦ Pay attention to the correct part number on renewing the ex‐  
pansion valve. ⇒ Electronic parts catalogue  
♦ Different characteristic curves are matched to the relevant cir‐  
cuit ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant  
circuit (vehicle-specific Workshop Manual) and ⇒ Electronic  
parts catalogue .  
♦ Depending on the version of the air conditioner compressor,  
there may be a valve on the high-pressure side of the com‐  
pressor which prevents liquid refrigerant from flowing back into  
the compressor after the air conditioner has been switched off.  
If an air conditioner compressor with such a valve is installed  
in a vehicle with a refrigerant circuit with an expansion valve,  
it may take a relatively long time before the pressure in the  
high-pressure side drops (the expansion valve is cold and the  
pressure in the low-pressure side increases rapidly after the  
compressor is switched off; the expansion valve is closed and  
the refrigerant can only flow slowly to the low-pressure side).  
If the air conditioner compressor is switched on, the pressure  
in the low-pressure side drops, the expansion valve is opened  
and the refrigerant can flow to the low-pressure side.  
3.2.11  
Expansion valve with shut-off valve  
Note  
There are different shut-off valve versions with different functions  
and designations. On the Audi Q5 hybrid, for example, the refrig‐  
erant shut-off valve 2 for hybrid battery - N517- (as illustrated  
below) is installed in the battery cooling module ⇒ Heating, air  
conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific  
Workshop Manual).  
3. General information on refrigerant circuit  
41  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
♦ The expansion valve -A- with -N517- -B- atomises the refrig‐  
erant flowing through and regulates the flow of refrigerant to  
the evaporator in the battery cooling module of the hybrid bat‐  
tery unit - AX1- so that - depending on the heat transferred -  
the vapour only turns into gas at the outlet of the evaporator.  
♦ When -N517- -B- is actuated by the electronic system, it is  
open and allows refrigerant to flow through the expansion  
valve -A- to the evaporator in the battery cooling module.  
♦ The expansion valve -A- with -N517- -B- is installed on vehi‐  
cles with battery cooling module. It is actuated in air condi‐  
tioning mode if the hybrid battery unit - AX1- needs to be  
cooled.  
♦ If -N517- -B- is actuated by the electronic system (e.g. by the  
battery regulation control unit - J840- ), it is opened and allows  
refrigerant to flow to the evaporator in the battery cooling mod‐  
ule according to its control characteristics.  
♦ The solenoid -N517- -B- (fitted at expansion valve -A-) is ac‐  
tivated e.g. by the battery regulation control unit - J840- ⇒ Cur‐  
rent flow diagrams, Electrical fault finding and Fitting locations  
and ⇒ Vehicle diagnostic tester (“Guided Fault Finding” for air  
conditioner and battery regulation) .  
♦ If, on a vehicle with two evaporators (one each in the air con‐  
ditioning unit and battery cooling module as e.g. on the Audi  
Q5 Hybrid), the measured temperature corresponds to or is  
below the specified value at one evaporator but the required  
specified value is not attained at the other evaporator, the sys‐  
tem is controlled as follows: the battery regulation control unit  
- J840- actuates the electric air conditioner compressor at a  
higher speed via the power and control electronics for electric  
drive - JX1- and the control unit for air conditioning compressor  
- J842- . This causes the cooling output of the air conditioner  
to increase and the pressure on the low-pressure side and the  
evaporator temperature to drop. If the required temperature  
value is then not reached at one evaporator, -J840- activates  
the refrigerant shut-off valve 1 for hybrid battery - N516- or the  
refrigerant shut-off valve 2 for hybrid battery - N517- so that  
refrigerant no longer flows through the evaporator which is too  
cold ⇒ Vehicle diagnostic tester in “Guided Fault Finding”  
mode for air conditioner .  
3.2.12  
Refrigerant shut-off valves  
Note  
♦ There are different shut-off valve versions with different func‐  
tions and designations. For example, the refrigerant shut-off  
valve 1 for hybrid battery - N516- (as illustrated below) is in‐  
stalled in the Audi Q5 hybrid ⇒ Heating, air conditioning; Rep.  
gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Man‐  
ual).  
♦ Different designations, depending on the function and vehicle  
⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit  
(vehicle-specific Workshop Manual).  
Shut-off valve with two switch statuses (open and closed)  
♦ Refrigerant shut-off valve 1 for hybrid battery - N516- (e.g. on  
the Audi Q5 hybrid)  
♦ Refrigerant shut-off valve for heater and air conditioner unit -  
N541- (e.g. on the Audi A3 e-tron)  
42  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
♦ Refrigerant shut-off valve for high-voltage battery heat ex‐  
changer - N542- (e.g. on the Audi A3 e-tron)  
♦ Refrigerant shut-off valve - V424- (e.g. on the Audi Q7 e-tron)  
♦ When the shut-off valve -A- is not actuated by the electronic  
system, it is open and allows refrigerant to flow to the evapo‐  
rator in the air conditioning unit.  
♦ The shut-off valve -A- is e.g. installed on vehicles with battery  
cooling module. It is actuated in hybrid mode if the air condi‐  
tioner is not set to cooling mode for the passenger compart‐  
ment, but the hybrid battery unit - AX1- needs to be cooled.  
♦ Observe the arrow -B- on the shut-off valve -A-; it shows the  
flow direction of the refrigerant (from condenser to evaporator  
in the air conditioning unit).  
♦ The solenoid -C- (fitted at the shut-off valve) is actuated e.g.  
by the battery regulation control unit - J840- ⇒ Current flow  
diagrams, Electrical fault finding and Fitting locations and ⇒  
Vehicle diagnostic tester in “Guided Fault Finding” mode for  
air conditioner and battery regulation .  
♦ If e.g. on a vehicle with two evaporators (one each in the air  
conditioning unit and battery cooling module as e.g. on the  
Audi Q5 Hybrid), the measured temperature corresponds to  
or is below the specified value at one evaporator but the re‐  
quired specified value is not attained at the other evaporator,  
the system is controlled as follows: the relevant control unit  
(e.g. the control unit for battery regulation - J840- on the Audi  
Q5 Hybrid) actuates the electric air conditioner compressor at  
a higher speed via the control unit for air conditioning com‐  
pressor - J842- . This causes the cooling output of the air  
conditioner to increase and the pressure on the low-pressure  
side and the evaporator temperature to drop. If the required  
temperature value is then not reached at one evaporator, the  
responsible control unit (e.g. -J840- on the Q5 hybrid) acti‐  
vates the refrigerant shut-off valve 1 for hybrid battery - N516-  
or the refrigerant shut-off valve 2 for hybrid battery - N517- so  
that refrigerant no longer flows through the evaporator which  
is too cold ⇒ Vehicle diagnostic tester in “Guided Fault Find‐  
ing” mode for air conditioner and ⇒ Heating, air conditioning;  
Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop  
Manual).  
Shut-off valves controlled via characteristic curves  
♦ Refrigerant shut-off valve 2 - N640- to refrigerant shut-off valve  
5 - N643- (e.g. on the Audi Q7 e-tron)  
♦ Refrigerant expansion valve 1 - N636- (e.g. on the Audi Q7 e-  
tron)  
3. General information on refrigerant circuit  
43  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
♦ Shut-off valve -A- is activated using a stepper motor -B- of the  
corresponding control unit via characteristic curves (open or  
closed).  
♦ If the shut-off valve is operating as a control valve (e.g. as the  
refrigerant expansion valve 1 - N636- on the Audi Q7) it is only  
opened as far as necessary until the specified temperature for  
the heat exchanger is reached ⇒ Heating, air conditioning;  
Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop  
Manual).  
♦ The shut-off valves activated by stepper motors have no speci‐  
fied rest position. They must therefore be moved to a specific  
position (open or closed) before any work is performed on the  
refrigerant circuit ⇒ Heating, air conditioning; Rep. gr. 87 ;  
Refrigerant circuit (vehicle-specific Workshop Manual).  
♦ Depending on the layout of the refrigerant circuit, several shut-  
off valves may be combined in one valve block (e.g. on the  
Audi Q7 e-tron) ⇒ Heating, air conditioning; Rep. gr. 87 ;  
Refrigerant circuit (vehicle-specific Workshop Manual).  
♦ The stepper motor is adapted and activated via data lines (LIN  
bus) by the corresponding control unit according to their fitting  
location ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant  
circuit (vehicle-specific Workshop Manual) and ⇒ Vehicle di‐  
agnostic tester (“Guided Fault Finding”).  
3.2.13  
Refrigerant line with internal heat ex‐  
changer  
In this refrigerant line, the hot refrigerant (liquid) flowing through  
the high-pressure side gives off energy to the cold refrigerant  
(gaseous or vaporous) flowing through the low-pressure side,  
thus enhancing the efficiency of the air conditioner.  
Note  
This illustration shows a refrigerant line with internal heat ex‐  
changer as fitted e.g. on the Audi A4 2008 > and the Audi A5  
Coupé 2008 > ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrig‐  
erant circuit (vehicle-specific Workshop Manual).  
A - Refrigerant line with internal heat exchanger  
B - Passages in refrigerant line, in which hot liquid refrigerant  
flows to evaporator (high-pressure side of refrigerant circuit)  
C - Passage in refrigerant line, in which cold gaseous or vaporous  
refrigerant flows to air conditioner compressor (low-pressure side  
of refrigerant circuit)  
3.2.14  
Quick-release couplings on refrigerant  
line  
WARNING  
Only release and open the quick-release couplings after com‐  
pletely discharging the refrigerant circuit.  
44  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Note  
♦ This illustration shows the quick-release couplings with a re‐  
frigerant line with internal heat exchanger as fitted e.g. on the  
Audi A4 2008 > and the Audi A5 Coupé 2008 > ⇒ Heating, air  
conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific  
Workshop Manual).  
♦ Removal of the refrigerant line -D- involves opening the re‐  
taining ring -A- with the refrigerant line release tool -T40149/-  
for example ⇒ Heating, air conditioning; Rep. gr. 87 ;  
Refrigerant circuit (vehicle-specific Workshop Manual).  
♦ Following removal of the applicable refrigerant line, renew the  
quick-release couplings -B- and -G- together with the corre‐  
sponding support ring -E- or -H- and the corresponding O-ring  
-F- or -J- ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant  
circuit (vehicle-specific Workshop Manual) and ⇒ Electronic  
parts catalogue .  
A - Retaining ring (in quick-release coupling, high-pressure side)  
B - Quick-release coupling with retaining ring (high-pressure side)  
C - Refrigerant line with internal heat exchanger  
D - Refrigerant line (high-pressure side)  
E - Support ring (high-pressure side)  
F - O-ring (“high-pressure side”)  
G - Quick-release coupling with retaining ring (low-pressure side)  
H - Support ring (low-pressure side)  
J - O-ring (“low-pressure side”)  
Note  
♦ There are different versions of the quick-release couplings  
-A- and -D-. With both versions of these quick-release cou‐  
plings, the refrigerant lines -C- can be released in the identical  
manner using the refrigerant line release tool -T40149/1- for  
example and removed.  
♦ With the quick-release coupling -A- fitted at the start of pro‐  
duction, the pins -B- become visible after fitting the refrigerant  
line -C- if the locked refrigerant line -C- is pulled in arrow di‐  
rection.  
♦ With the quick-release coupling -D- installed from model year  
2010 onwards (gradual introduction), the refrigerant line -C- is  
installed in the same way as with the quick-release coupling  
-A-. If, on this version, the refrigerant line -C- is pulled in the  
direction of the arrow after it is assembled, the snap ring -E-  
emerges from the quick-release coupling -D-, showing that the  
retaining ring -F- is completely locked onto the refrigerant line  
-C-. The snap ring -E- is then to be detached from the refrig‐  
erant line -C-.  
3. General information on refrigerant circuit  
45  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.2.15  
O-rings  
These rings seal the joints between the individual components of  
the refrigerant circuit.  
Only O-rings resistant to R134a refrigerant and the related refrig‐  
erant oils are to be used. This is guaranteed if genuine replace‐  
ment parts are used.  
O-rings:  
– Use only once.  
– Observe correct diameters -a- and -b-.  
– Before installing, lubricate lightly with refrigerant oil ⇒ Heating,  
air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-spe‐  
cific Workshop Manual) and ⇒ Electronic parts catalogue .  
Note  
The colour coding of O-rings for R134a refrigerant circuits has  
been discontinued. Black and coloured O-rings are used ⇒ Elec‐  
tronics parts catalogue and ⇒ Heating, air conditioning; Rep. gr.  
87 ; Refrigerant circuit (vehicle-specific Workshop Manual).  
3.2.16  
Pipes and hoses of refrigerant circuit  
The mixture of refrigerant oil and refrigerant R134a corrodes cer‐  
tain metals (e.g. copper) and alloys and dissolves certain hose  
materials. Therefore, always use genuine replacement parts.  
The pipes and hoses are joined with bolted connections or special  
connectors.  
Note  
Observe specified torques for bolted joints and use the specified  
release tools for connectors.  
3.2.17  
High-pressure safety valve  
The high-pressure safety valve is attached to the air conditioner  
compressor or the receiver.  
The valve opens at a pressure of approx. 38 bar and closes again  
when the pressure has dropped (approx. 30 bar).  
Not all the refrigerant escapes.  
46  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Note  
♦ Depending on the version, a transparent plastic disc -B- may  
be attached to the high-pressure safety valve -A-. The disc  
breaks off as soon as the valve is actuated.  
♦ Depending on the version of the high-pressure safety valve  
-A-, there may also be a cover -C- on the high-pressure safety  
valve -A-. Should the pressure in the refrigerant circuit ever  
exceed the opening pressure of the high-pressure safety valve  
-A-, causing the high-pressure safety valve to open, the re‐  
frigerant does not emerge in one direction but is distributed  
through the openings -D- under the cover -C-.  
♦ Should it be necessary to renew a high-pressure safety valve  
-A-, please observe the correct tightening torque when instal‐  
ling (dependent on air conditioner compressor manufacturer  
and version). On air conditioner compressors manufactured  
by Denso (or Nippondenso), Sanden or Zexel/Valeo, an O-ring  
is fitted (tightening torque: currently 10 Nm for Denso and  
Zexel/Valeo; 15 Nm for Sanden). On Delphi air conditioner  
compressors, a seal is fitted (tightening torque: currently 15  
Nm).  
♦ Renew seal/O-ring ⇒ Electronic parts catalogue .  
♦ If the seal/O-ring fitted at the high-pressure safety valve can‐  
not be supplied as a replacement part, the removed compo‐  
nent can be re-installed as an exception; it must be checked  
for damage before being re-installed. If the removed seal/O-  
ring is damaged or deformed, it must be replaced by a com‐  
mercially available component ⇒ Electronic parts catalogue .  
♦ After charging the refrigerant circuit, check the installed high-  
pressure safety valve for leaks, e.g. with an electronic leak  
detector.  
3.2.18  
Non-return valves  
Non-return valves separate the refrigerant circuit into different  
sections.  
Note  
♦ The non-return valve -3- in the illustration is installed e.g. on  
the Audi Q7 e-tron.  
♦ Non-return valves in the refrigerant circuit have a specific  
holding pressure (approx. 0.1 bar or 100 mbar) in the forward  
direction. All electrically activated valves must therefore be  
open so that the refrigerant circuit can be evacuated fully (re‐  
sidual pressure less than 5 mbar).  
♦ Depending on the version, there may be a sticker indicating  
the direction of flow.  
3. General information on refrigerant circuit  
47  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.3  
Design of refrigerant circuit  
⇒ “3.3.1 Refrigerant circuit with expansion valve and evaporator”,  
page 48  
⇒ “3.3.2 Refrigerant circuit with restrictor and reservoir”,  
page 48  
⇒ “3.4 Refrigerant circuit with electrically driven air conditioner  
compressor”, page 49  
3.3.1  
Refrigerant circuit with expansion valve  
and evaporator  
The following illustration only shows the general layout of a typical  
refrigerant circuit; refer to the vehicle-specific Workshop Manual  
for the layout of that vehicle's refrigerant circuit ⇒ Heating, air  
conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific  
Workshop Manual).  
1 - Evaporator  
2 - Expansion valve  
3 - Valve for extraction, charging and measurement  
4 - Sight glass (not fitted with R134a circuits)  
5 - Receiver with dryer  
6 - Condenser  
7 - Air conditioner compressor  
Note  
Arrows show direction of refrigerant flow.  
3.3.2  
Refrigerant circuit with restrictor and  
reservoir  
The following illustration only shows the general layout of a typical  
refrigerant circuit; refer to the vehicle-specific Workshop Manual  
for the layout of that vehicle's refrigerant circuit ⇒ Heating, air  
conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific  
Workshop Manual).  
1 - Air conditioner compressor  
2 - Condenser  
3 - Restrictor  
4 - Evaporator  
5 - Reservoir  
Note  
Arrows show direction of refrigerant flow.  
48  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.4  
Refrigerant circuit with electrically driven  
air conditioner compressor  
Vehicles with high-voltage system (hybrid vehicles)  
High voltage! Danger to life!  
The voltage levels in the high-voltage system constitute a safety  
hazard. Danger of severe or fatal injuries from electric shock.  
– Persons with life-sustaining or other electronic medical devi‐  
ces in or on their body must not perform any work on the high-  
voltage system. Such medical devices include internal anal‐  
gesic pumps, implanted defibrillators, pacemakers, insulin  
pumps and hearing aids.  
– The high-voltage system must be de-energised by a suitably  
qualified person.  
Risk of injury - engine may start unexpectedly  
It is difficult to determine whether the drive system of an electric  
vehicle or hybrid vehicle is active. Moving parts can trap or draw  
in parts of the body.  
– Switch off ignition.  
– Place ignition key outside vehicle.  
Risk of damage to high-voltage wiring  
Incorrect handling may result in damage to the insulation of high-  
voltage wires or high-voltage connectors.  
– Never use high-voltage wiring or high-voltage connectors as  
a support.  
– Never prop tools against high-voltage wiring or high-voltage  
connectors.  
– Never bend or kink high-voltage wiring.  
– Pay attention to coding when connecting high-voltage con‐  
nections.  
♦ For all work on vehicles with high-voltage system, note addi‐  
tional warnings for working on such vehicles  
⇒ “1 Warning instructions when working on vehicles with high-  
voltage system”, page 1 .  
♦ If work near high-voltage system components is necessary,  
perform a visual check of the high-voltage components and  
wires to check for damage ⇒ page 2 .  
♦ If work on high-voltage system components is necessary, de-  
energise high-voltage system ⇒ Rep. gr. 93 ; De-energising  
high-voltage system or ⇒ Electrical system; Rep. gr. 93 ; De-  
energising high-voltage system .  
3. General information on refrigerant circuit  
49  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Note  
The following illustration shows the refrigerant circuit fitted in the  
Audi Q5 hybrid as an example; refer to the vehicle-specific Work‐  
shop Manual for the layout of that vehicle's refrigerant circuit ⇒  
Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-  
specific Workshop Manual).  
Arrows show direction of refrigerant flow.  
1 - Electrically driven air condi‐  
tioner compressor  
❑ With control unit for air  
conditioning compres‐  
sor - J842- and electrical  
air conditioner compres‐  
sor - V470-  
2 - Condenser  
❑ With receiver and desic‐  
cant cartridge  
3 - Service connection (high-  
pressure side)  
4 - Refrigerant shut-off valve 1  
for hybrid battery - N516-  
❑ Only on vehicles with  
battery cooling module  
for hybrid battery unit -  
AX1-  
Note  
-N516- is activated, for e
the battery needs to be
the air conditioner is not
ing mode for the passen
partment (valve open wh
activated).  
5 - Expansion valve  
❑ At evaporator in air con‐  
ditioning unit  
6 - Evaporator  
❑ Evaporator in air condi‐  
tioning unit  
7 - Expansion valve with refrig‐  
erant shut-off valve 2 for hybrid battery - N517-  
❑ At evaporator in battery cooling module  
❑ Only on vehicles with battery cooling module for hybrid battery unit - AX1-  
Note  
-N517- is activated if battery needs  
to be cooled (closed when not acti‐  
vated).  
8 - Evaporator  
❑ Evaporator in battery cooling module  
❑ Only on vehicles with battery cooling module for hybrid battery unit - AX1-  
50  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
9 - Service connection (low-pressure side)  
3.5  
Connections for quick-release coupling  
in refrigerant circuit  
•
•
•
•
Only use valves and connections that are resistant to R134a  
refrigerant and related refrigerant oils.  
There are different connections (outer diameter) for high and  
low-pressure sides.  
Discharge refrigerant circuit before removing valves or valve  
cores.  
Always screw on sealing caps.  
Layout in vehicle ⇒ Heating, air conditioning; Rep. gr. 87 ; Re‐  
frigerant circuit (vehicle-specific Workshop Manual)  
WARNING  
Risk of injury (frostbite).  
Refrigerant may escape if the refrigerant circuit has not been  
discharged.  
Extract refrigerant before opening refrigerant circuit. Renewed  
evaporation may create pressure in refrigerant circuit if refrig‐  
erant circuit is not opened within 10 minutes following extrac‐  
tion. Extract refrigerant again.  
3. General information on refrigerant circuit  
51  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
⇒ “3.5.1 Connections with Schrader valve (needle valve)”,  
page 52  
⇒ “3.5.2 Connections with primary sealing valve (ball valve)”,  
page 52  
⇒ “3.5.3 Differences in service connections depending on refrig‐  
erant (R134a or R1234yf)”, page 55  
3.5.1  
Connections with Schrader valve (nee‐  
dle valve)  
♦ -A- Service connection (soldered in)  
♦ -B- Valve core (designation: Schrader valve or needle valve)  
♦ -C- O-ring (for valve)  
♦ -D- Sealing cap with seal  
Note  
♦ After connecting, carefully screw handwheel of service cou‐  
pling into quick-release coupling adapter only to the extent  
required to reliably open valve in service connection (observe  
pressure gauge; do not open valve too far).  
♦ When removing and installing valve core -B- with refrigerant  
circuit discharged, use e.g. adapter from socket - T10364- .  
♦ Take care when tightening valve core -B- (low torque).  
♦ There are different versions of these valves; therefore tight‐  
ening torques vary. For a valve core -B- with a VG5 thread  
(5.2 x 0.7 mm, tyre valve) the tightening torque is 0.4 Nm  
+/- 0.1 Nm; for a valve core with an M6 x 0.75 mm thread, the  
tightening torque is 0.9 Nm +/- 0.1 Nm, and for a valve core  
with an M8 x 1.0 mm thread, the tightening torque is  
2.0 Nm +/- 0.2 Nm.  
♦ There are different versions of these valves, valve cores and  
corresponding sealing caps. Note the correct version of the  
valve core and correct assignment of the sealing caps ⇒ Elec‐  
tronic parts catalogue .  
3.5.2  
Connections with primary sealing valve  
(ball valve)  
WARNING  
Before unscrewing the connection, connect the air conditioner  
service station and extract refrigerant. The refrigerant circuit  
must be empty; danger of injury.  
52  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Connection with high-pressure valve  
1 - Connection with internal thread (soldered in)  
2 - O-ring (version and identification: black or coloured ⇒ Elec‐  
tronic parts catalogue )  
3 - Valve with external thread and groove for O-ring (designa‐  
tion: ball valve)  
4 - Seal for cap  
5 - Cap  
Depending on the vehicle, high pressure may not be available at  
the service connection on the high-pressure side in all air condi‐  
tioner operating modes (e.g. on the Audi Q7 e-tron). The senders  
installed in the refrigerant circuit must therefore be used to check  
that the air conditioner in these vehicles is functioning properly ⇒  
Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-  
specific Workshop Manual) and ⇒ Vehicle diagnostic tester in  
“Guided Fault Finding” mode.  
Note  
♦ After connecting, carefully screw handwheel of service cou‐  
pling into quick-release coupling adapter only to the extent  
required to reliably open valve in service connection (observe  
pressure gauge; do not open valve too far).  
♦ When removing and installing valve -3- with refrigerant circuit  
discharged, use e.g. an adapter from socket - T10364- .  
♦ There are different versions of these valves (with internal or  
external thread); therefore the tightening torques may vary.  
For the valves -3- currently in use (external thread M12 x 1.5  
mm) the tightening torque is 9 Nm +/- 1 Nm.  
♦ There are different versions of these valves and the corre‐  
sponding sealing caps. Note the correct version of the valve  
and correct assignment of the sealing cap ⇒ Electronic parts  
catalogue .  
3. General information on refrigerant circuit  
53  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Connection with low-pressure valve  
1 - Connection with external thread and groove for O-ring (sol‐  
dered in)  
2 - O-ring (version and identification: black or coloured ⇒ Elec‐  
tronic parts catalogue )  
3 - Valve with internal thread  
4 - Seal for cap  
5 - Cap  
Note  
♦ Screw handwheel of service coupling into quick-release cou‐  
pling adapter carefully and only to the extent required to  
reliably open valve in service connection (observe pressure  
gauge; do not open valve too far).  
♦ When removing and installing valve -3- with refrigerant circuit  
discharged, use e.g. an adapter from socket - T10364- .  
♦ There are different versions of these valves (with internal or  
external thread); therefore the tightening torques may vary.  
For the valves -3- currently in use (internal thread  
M10 x 1.25 mm) the tightening torque is 9 Nm +/- 1 Nm.  
♦ There are different versions of these valves and the corre‐  
sponding sealing caps. Note the correct version of the valve  
and correct assignment of the sealing cap ⇒ Electronic parts  
catalogue .  
54  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.5.3  
Differences in service connections de‐  
pending on refrigerant (R134a or  
R1234yf)  
Note  
♦ Only use valves and connections which are resistant to the  
corresponding refrigerant (R134a and/or R1234yf) and related  
refrigerant oils ⇒ Electronic parts catalogue .  
♦ The service connections for the refrigerant circuits are de‐  
signed such that only the specified service couplings for the  
specified refrigerant (R134a or R1234yf) can be connected.  
♦ These illustrations show service connections in which a  
Schrader valve (needle valve or push pin) is installed. How‐  
ever, depending on the vehicle version or the type of refriger‐  
ant etc., service connections with a primary sealing valve (ball  
valve) may also be installed (different technology)  
⇒ “3.5.2 Connections with primary sealing valve (ball valve)”,  
page 52 .  
♦ Layout in vehicle and on refrigerant circuit ⇒ Heating, air con‐  
ditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific  
Workshop Manual).  
♦ There are different connections (outer diameter) for high and  
low-pressure sides.  
♦ Discharge refrigerant circuit before removing valves or valve  
cores  
⇒ “5.3.3 Discharging refrigerant circuit with air conditioner  
service station”, page 84 .  
♦ Removing and installing valve from service connection (low  
and high-pressure sides)  
⇒ “3.5.1 Connections with Schrader valve (needle valve)”,  
page 52 .  
♦ Always screw on sealing caps with seal.  
3. General information on refrigerant circuit  
55  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Service connections (refrigerant R134a and R1234yf)  
WARNING  
Before removing valves -B, E-, connect the air conditioner  
service station and extract refrigerant. Refrigerant circuit must  
be  
empty;  
danger  
of  
injury  
⇒ “5.3.3 Discharging refrigerant circuit with air conditioner  
service station”, page 84 .  
♦ Cap for service connection (high-pressure side) -A- with seal  
-G-  
♦ Valve core on high-pressure side (version: Schrader valve or  
needle valve) -B-  
♦ Service connection (high-pressure side) -C-  
♦ Cap for service connection (low-pressure side) -D- with seal  
-G-  
♦ Valve core on low-pressure side (version: Schrader valve or  
needle valve) -E-  
♦ Service connection (low-pressure side) -F-  
Note  
♦ Service connections -C, F- for refrigerant R134a and R1234yf  
are available in different versions (depending on manufactur‐  
er), with different sealing caps -A, D- and valves -B, E-. Ensure  
correct assignment ⇒ Electronic parts catalogue .  
♦ Sealing caps -A, D- for the service connections on the R134a  
refrigerant circuit are currently black. The sealing caps for the  
service connections on the R1234yf refrigerant circuit are cur‐  
rently grey. The refrigerant type (e.g. “R1234yf”) may also be  
printed on the sealing caps.  
♦ After connecting, carefully screw the handwheel of the service  
coupling into the quick-release coupling adapter only to the  
extent required to reliably open the valve -B, E- in the service  
connection (observe the pressure gauge; do not open the  
valve -B, E- too far).  
♦ The service connections -C, F- for R134a and R134yf refrig‐  
erant circuits are designed such that only the service couplings  
specified for the corresponding refrigerant can be connected  
(different dimensions ⇒ page 57 ).  
♦ Service connections -C, F-, for example, are soldered into a  
refrigerant line and therefore cannot be renewed separately.  
♦ To remove and install the valves -B, E- (with the refrigerant  
circuit drained), make use of an adapter from the socket -  
T10364- for example.  
♦ Take care when tightening the valves -B, E- (low torque).  
♦ These valves are available in different versions with differing  
tightening torques. Tightening torque for valve core -C-with a  
VG5 thread (5.2 x 0.7 mm tyre valve): 0.4 Nm. +- 0.1 Nm;  
tightening torque for valve core with an M6 x 0.75 mm thread:  
0.9 Nm +- 0.1 Nm; tightening torque for valve core with an M8  
x 1.0 mm: 2.0 Nm +- 0.2 Nm.  
♦ There are different versions of valve caps -A, D-; therefore  
tightening torques vary. Tightening torque for valve cap with  
M8 x 1 mm or M10 x 1 mm thread: 0.4 Nm +- 0.1 Nm.  
56  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Dimensions of service connections  
♦ Valve core -A- (different versions; refer to ⇒ Electronic parts  
catalogue )  
♦ Service connection -B- (different versions on high-pressure  
and low-pressure side depending on refrigerant)  
Dimensions of serv‐ Service connec‐  
ice connections -B- tion (refrigerant  
R134a)  
Service connection  
(refrigerant  
R1234yf)  
High-  
Low-  
High- Low-  
pressure pressure  
side side  
pressure pres‐  
side  
sure  
side  
Outer diameter -D1-  
16.0 mm 13.0  
17.0 mm 14.0 mm  
13.0 mm 12.0 mm  
9.0 mm 4.75 mm  
12.5 mm 7.2 mm  
mm  
Outer diameter -D2- 14.0 mm 11.0  
mm  
Offset -L1-  
4.6 mm 6.15  
mm  
Offset -L2-  
8.16 mm 9.16  
mm  
Installation position of 6.1 - 7.1 6.1 - 7.1 8.3 - 9.3 8.3 - 9.3  
valve (not actuated) mm  
-C-  
mm  
mm  
mm  
3.6  
Switches and senders in refrigerant cir‐  
cuit and related connections  
Note  
Refer to vehicle-specific refrigerant circuit for switching pres‐  
sures, removing and installing switches and location/design of  
switches ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant  
circuit (vehicle-specific Workshop Manual).  
3. General information on refrigerant circuit  
57  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
⇒ “3.6.1 High-pressure switch for air conditioning system F23 ”,  
page 58  
⇒ “3.6.2 High-pressure switch for magnetic clutch F118 ”,  
page 58  
⇒ “3.6.3 Low-pressure switch for air conditioning system F73 ”,  
page 59  
⇒ “3.6.5 Air conditioning system pressure switch F129 ”,  
page 59  
⇒ “3.6.6 High-pressure sender G65 and pressure sender for re‐  
frigerant circuit G805 ”, page 60  
⇒ “3.6.7 Refrigerant pressure and temperature sender”,  
page 61  
⇒ “3.6.4 Connections with valve for refrigerant circuit switches”,  
page 59  
⇒ “3.6.8 Air conditioner compressor regulating valve N280 ”, page  
64  
⇒ “3.6.9 Air conditioner compressor speed sender G111 ”, page  
64  
⇒ “3.6.10 Refrigerant temperature sender G454 ”, page 65  
3.6.1  
High-pressure switch for air conditioning  
system - F23-  
Function:  
Switches the radiator fan up to the next speed setting in the event  
of a pressure increase in the refrigerant circuit (approx. 16 bar).  
3.6.2  
High-pressure switch for magnetic  
clutch - F118-  
Function:  
Switches off the air conditioner compressor in the event of excess  
pressure in the refrigerant circuit (approx. 32 bar).  
58  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.6.3  
Low-pressure switch for air conditioning  
system - F73-  
Function:  
Switches off the air conditioner compressor in the event of a pres‐  
sure drop in the refrigerant circuit (approx. 2 bar).  
3.6.4  
Connections with valve for refrigerant  
circuit switches  
•
•
Different threads for switches on high- and low pressure sides.  
Only valves and O-rings resistant to R134a refrigerant and the  
related refrigerant oils are to be used.  
A - Connection (soldered in)  
B - O-ring  
C - Valve (with O-ring)  
Note  
When removing and installing the valve core -C- with refrigerant  
circuit discharged, use e.g. adapter from socket - T10364- (tight‐  
ening torque ⇒ page 52 ).  
3.6.5  
Air conditioning system pressure switch  
- F129-  
This pressure switch has 3 functions:  
1. Switches the radiator fan up to the next speed setting in the  
event of a pressure increase (approx. 16 bar) in the refrigerant  
circuit.  
2. Switches off the air conditioner in the event of excessive pres‐  
sure (approx. 32 bar) caused, for example, by inadequate engine  
cooling.  
3. Switches off the air conditioner in the event of insufficient pres‐  
sure (approx. 2 bar) caused, for example, by a loss of refrigerant.  
Note  
The air conditioning system pressure switch - F129- replaces the  
high-pressure switch for air conditioning system - F23- , the low-  
pressure switch for air conditioning system - F73- and the high-  
pressure switch for magnetic clutch - F118- .  
3. General information on refrigerant circuit  
59  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.6.6  
High-pressure sender - G65- and pres‐  
sure sender for refrigerant circuit -  
G805-  
♦ -G65- is installed instead of the air conditioning system pres‐  
sure switch - F129- or the refrigerant pressure and tempera‐  
ture sender - G395- .  
♦ On some vehicles from a certain version and production date  
onwards, -G805- replaces -G65- .  
♦ When voltage is applied, one version of -G65- generates a  
square-wave signal and the other generates a data telegram.  
This signal changes with the pressure in the system. The other  
version and -G805- exchange information with the corre‐  
sponding control unit via the data bus (e.g. via the “LIN bus”)  
when voltage is applied ⇒ Heating, air conditioning; Rep. gr.  
87 ; Refrigerant circuit (vehicle-specific Workshop Manual).  
♦ -G65- is installed e.g. in the Audi A3 2005> and the Audi Q3.  
It transmits its measured values as square-wave signals to the  
corresponding control unit (e.g. to the air conditioning system  
control unit - J301- or the Climatronic control unit - J255- ). -  
G65- is installed e.g. in the Audi Q7 2016>. It transmits its  
measured values via a “LIN bus” ⇒ Vehicle diagnostic tester  
(“Self-diagnosis” or “Guided Fault Finding” function for air con‐  
ditioner) and ⇒ Current flow diagrams, Electrical fault finding  
and Fitting locations.  
♦ -G805- is installed e.g. in the Audi A3 2013>. It exchanges  
information with the corresponding control unit over a data bus  
(e.g. in the Audi A3 with the air conditioning system control unit  
- J301- or the Climatronic control unit - J255- ). ⇒ Current flow  
diagrams, Electrical fault finding and Fitting locations  
♦ There are different versions of the refrigerant pressure and  
temperature sender - G395- , the pressure sender for refrig‐  
erant circuit - G805- and the high-pressure sender - G65- ;  
depending on the version, they can currently only be distin‐  
guished by the part number. Therefore pay attention to the  
correct assignment when renewing the components (part  
number ⇒ Electronic parts catalogue ). Reason: These two  
senders emit different signals, and the relevant control units  
can only evaluate the signal to which they have been matched  
⇒ Vehicle diagnostic tester (“Self-diagnosis” or “Guided Fault  
Finding” function for air conditioner), and ⇒ Heating, air con‐  
ditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific  
Workshop Manual).  
♦ -G65- and -G805- transmit only the measured value for the  
pressure in the refrigerant circuit to the connected control unit.  
-G395- transmits the measured value for the pressure in the  
refrigerant circuit and the measured temperature to the con‐  
nected control unit. Even if only the pressure signal is evalu‐  
ated for a vehicle, a vehicle in which -G65- or -G805- is  
intended to be installed must not be fitted with a -G395- ⇒  
Electronic parts catalogue .  
♦ The control units downstream (radiator fan control unit, engine  
control unit, operating and display unit for front air conditioning  
system - E87- or Climatronic control unit - J255- etc.) use this  
signal to calculate the pressure in the refrigerant circuit; the  
control units then actuate the radiator fans, motor and air con‐  
ditioning system magnetic clutch - N25- accordingly or modify  
the activation of the air conditioner compressor regulating  
valve - N280- ⇒ Vehicle diagnostic tester (“Self-diagnosis” or  
“Guided Fault Finding” function) and ⇒ Heating, air condition‐  
ing; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Work‐  
shop Manual).  
60  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.6.7  
Refrigerant pressure and temperature  
sender  
There are different versions of these senders with different func‐  
tions and designations. For the exact designation, assignment  
and information on the corresponding function, refer to ⇒ Heating,  
air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific  
Workshop Manual).  
WARNING  
Risk of injury (frostbite).  
Refrigerant may escape if the refrigerant circuit has not been  
discharged.  
There are different versions of these senders (sender for a  
connection on the refrigerant circuit with or without valve) ⇒  
Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (ve‐  
hicle-specific Workshop Manual).  
♦ Before loosening the bolt securing the sender, check the  
version of the sender ⇒ Heating, air conditioning; Rep.  
gr. 87 ; Refrigerant circuit (vehicle-specific Workshop  
Manual).  
♦ With a sender for connecting to a refrigerant circuit without  
valve. Extract the refrigerant before undoing the threaded  
joint. Renewed evaporation may create pressure in the  
refrigerant circuit if the sender is not removed within 10  
minutes following extraction. Extract refrigerant again.  
Senders for a connection with valve at refrigerant circuit  
Note  
♦ There are different versions of these senders with different  
functions and designations. For example, the refrigerant pres‐  
sure and temperature sender - G395- (as illustrated below) is  
installed in the Audi A4, Audi Q5 and Audi Q5 hybrid ⇒ Heat‐  
ing, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-  
specific Workshop Manual).  
♦ Different designations, depending on the function and vehicle  
⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit  
(vehicle-specific Workshop Manual).  
3. General information on refrigerant circuit  
61  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Possible designations for these senders  
♦ Refrigerant pressure and temperature sender - G395- (e.g. on  
the Audi Q5 hybrid)  
♦ High-pressure sender - G65- (e.g. on the Audi A4)  
♦ Pressure sender for refrigerant circuit - G805- (e.g. on the Audi  
A3 e-tron)  
Note  
The pressure sender for refrigerant circuit - G805- is installed e.g.  
instead of the high-pressure sender - G65- or the refrigerant pres‐  
sure and temperature sender - G395- ⇒ Heating, air conditioning;  
Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Man‐  
ual).  
♦ There are different versions of the refrigerant pressure and  
temperature sender - G395- , the pressure sender for refrig‐  
erant circuit - G805- and the high-pressure sender - G65- ;  
depending on the version, they can currently only be distin‐  
guished by the part number. Therefore pay attention to the  
correct assignment when renewing the components (part  
number ⇒ Electronic parts catalogue ). Reason: These two  
senders emit different signals, and the relevant control units  
can only evaluate the signal to which they have been matched  
⇒ Vehicle diagnostic tester (“Self-diagnosis” or “Guided Fault  
Finding” function for air conditioner), and ⇒ Heating, air con‐  
ditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific  
Workshop Manual).  
♦ When voltage is applied, the refrigerant pressure and temper‐  
ature sender - G395- (and the pressure sender for refrigerant  
circuit - G805- ) exchange information with the corresponding  
control unit via the data bus (e.g. “LIN bus”). The correspond‐  
ing control unit uses this information to calculate the pressure  
(and temperature) in the refrigerant circuit; any faults detected  
are signalled to the control unit.  
♦ -G395- transmits the measured value for the pressure in the  
refrigerant circuit and the measured temperature to the con‐  
nected control unit. -G805- transmits only the measured value  
for the pressure in the refrigerant circuit to the connected con‐  
trol unit. Even if only the pressure signal is evaluated on most  
vehicles, a vehicle in which a -G395- is intended to be installed  
must not be fitted with a -G805- ⇒ Electronic parts catalogue .  
♦ The temperature measured by the refrigerant pressure and  
temperature sender - G395- differs from the actual tempera‐  
ture of the refrigerant in the refrigerant circuit due to the design  
of -G395- and the fitting location. Therefore it is currently not  
evaluated by all control units and used for air conditioner con‐  
trol ⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit  
(vehicle-specific Workshop Manual).  
♦ This information is used, for example, by the operating and  
display unit ( Climatronic control unit - J255- ) or the onboard  
supply control unit - J519- to calculate the pressure in the re‐  
frigerant circuit and to actuate the control units downstream  
(radiator fan control unit, engine control unit etc.) by way of the  
data bus. These control units then activate e.g. the air condi‐  
tioning system magnetic clutch - N25- , the radiator fans and  
the motor accordingly ⇒ Vehicle diagnostic tester , “Self-di‐  
agnosis” or “Guided Fault Finding” function and ⇒ Heating, air  
conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific  
Workshop Manual).  
62  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Senders for a connection without valve at refrigerant circuit  
Note  
♦ There are different versions of these senders with different  
functions and designations. For example, the refrigerant pres‐  
sure and temperature sender - G395- (as illustrated below) is  
installed in the Audi Q7 e-tron ⇒ Heating, air conditioning;  
Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop  
Manual).  
♦ Different designations, depending on the function and vehicle  
⇒ Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit  
(vehicle-specific Workshop Manual).  
Possible designations for these senders  
♦ Refrigerant pressure and temperature sender - G395- (e.g. on  
the Audi Q7 e-tron)  
♦ Refrigerant pressure and temperature sender 2 - G826- (e.g.  
on the Audi Q7 e-tron)  
♦ Refrigerant pressure and temperature sender 3 - G827- (e.g.  
on the Audi Q7 e-tron)  
There are different versions of these senders -A-; depending on  
the version, they can currently only be distinguished by the part  
number or by the printed designation -B- if the part number is the  
same. Therefore pay attention to the correct assignment when  
renewing the components; for part number and designation, refer  
to ⇒ Electronic parts catalogue and ⇒ Heating, air conditioning;  
Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Man‐  
ual).  
When voltage is applied, these senders exchange information  
with the corresponding control unit via the data bus (e.g. via the  
“LIN bus”). The corresponding control unit uses this information  
to calculate the pressure (and temperature) in the refrigerant cir‐  
cuit; any faults detected are signalled to the control unit ⇒ Vehicle  
diagnostic tester (“Guided Fault Finding”).  
The corresponding control unit uses this information to calculate  
the pressure in the refrigerant circuit and activates downstream  
control units or components (control unit for radiator fan, pumps,  
valves etc.) via the data bus according to requirements ⇒ Vehicle  
diagnostic tester (“Guided Fault Finding”) and ⇒ Heating, air con‐  
ditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Work‐  
shop Manual).  
3. General information on refrigerant circuit  
63  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.6.8  
Air conditioner compressor regulating  
valve - N280-  
The regulating valve is installed in the air conditioner compressor.  
It is activated by the operating and display unit for front air con‐  
ditioning system - E87- , the air conditioning system control unit -  
J301- or the Climatronic control unit - J255- (possibly via the data  
bus and an additional control unit, depending on the vehicle) ⇒  
Heating, air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-  
specific Workshop Manual). The regulating valve influences the  
pressure on the low-pressure side and thus regulates the tem‐  
perature in the evaporator.  
Note  
The air conditioner compressor regulating valve - N280- is part of  
the air conditioner compressor and cannot be renewed separately  
on all air conditioner compressors ⇒ Electronic parts catalogue  
and  
⇒ “9.1.8 Removing/installing and renewing air conditioner com‐  
pressor regulating valve N280 ”, page 285 .  
3.6.9  
Air conditioner compressor speed send‐  
er - G111-  
Inductive sender  
The sender pulses (4 per compressor revolution) and the engine  
speed enable the operating and display unit for front air condi‐  
tioning system - E87- or the Climatronic control unit - J255- to  
calculate the belt slip.  
If the belt slip exceeds a specified value, the air conditioner com‐  
pressor is switched off by the control unit via the magnetic clutch.  
Note  
♦ This component is installed in Audi vehicles with compressor  
drive via poly V-belt and Zexel compressor ⇒ Heating, air  
conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific  
Workshop Manual).  
♦ The logo of the compressor manufacturer “Zexel” attached to  
the air conditioner compressor was modified from “Zexel” to  
“Valeo” from year of production 2006 onwards (change in  
manufacturer's name).  
64  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.6.10  
Refrigerant temperature sender - G454-  
The refrigerant temperature sender (with a temperature-sensitive  
resistor) is installed, for example, in the high-pressure line near  
the air conditioner compressor (only for certain vehicles manu‐  
factured within a specific period, e.g. on Audi Q7 2007>).  
In the refrigerant circuit, there is a direct relationship between  
temperature and pressure. If there is insufficient refrigerant in the  
circuit, the temperature in the refrigerant circuit during air condi‐  
tioner operation will increase more sharply than envisaged for this  
pressure.  
Note  
♦ Installed e.g. in Audi Q7 with certain engines ⇒ Heating, air  
conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific  
Workshop Manual) and ⇒ Current flow diagrams, Electrical  
fault finding and Fitting locations.  
♦ The operating and display unit ( Climatronic control unit -  
J255- ) evaluates the pressure and the temperature in the  
refrigerant circuit and switches off the air conditioner com‐  
pressor if the temperature increases above the value stored  
for this pressure ⇒ Heating, air conditioning; Rep. gr. 87 ;  
Refrigerant circuit (vehicle-specific Workshop Manual) and ⇒  
Vehicle diagnostic tester (“Self-diagnosis” or “Guided Fault  
Finding” function for air conditioner).  
3.7  
Electrical components not installed in  
refrigerant circuit  
⇒ “3.7.1 Radiator fan control unit J293 ”, page 65  
3.7.1  
Radiator fan control unit - J293-  
This control unit switches the magnetic clutch and thus the air  
conditioner compressor on and off. It switches the radiator fans  
and calculates the pressure in the refrigerant circuit on vehicles  
with a high-pressure sender - G65- . Refer to ⇒ Current flow dia‐  
grams, Electrical fault finding and Fitting locations and ⇒ Heating,  
air conditioning; Rep. gr. 87 ; Refrigerant circuit (vehicle-specific  
Workshop Manual).  
3.8  
Pressures and temperatures in refriger‐  
ant circuit  
Caution  
♦ When working on the refrigerant circuit, observe generally  
valid safety precautions and pressure vessel regulations.  
The pressures and temperatures in the refrigerant circuit depend  
on the instantaneous operating statuses (e.g. engine speed, ra‐  
diator fan speed 1, 2, or 3, engine temperature, air conditioner  
compressor on or off) as well as environmental influences (e.g.  
ambient temperature, humidity, required cooling output).  
3. General information on refrigerant circuit  
65  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
On vehicles with air conditioner compressor regulating valve -  
N280- the pressure on the low-pressure side is altered by actuat‐  
ing -N280- .  
On vehicles with an electrical air conditioner compressor - V470- ,  
the pressure in the refrigerant circuit (high-pressure and low-  
pressure sides) is regulated via the speed of the air conditioner  
compressor.  
On vehicles with an electrical air conditioner compressor - V470-  
where the air conditioner is used not only to cool the passenger  
compartment but also to cool high-voltage system components  
and as a heat pump to heat the passenger compartment, different  
conditions, pressures and temperatures apply in the refrigerant  
circuit (e.g. on the Audi Q7 e-tron) ⇒ Vehicle diagnostic tester in  
“Guided Fault Finding” mode and ⇒ Heating, air conditioning;  
Rep. gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Man‐  
ual).  
For this reason, the values given in the following table are for ref‐  
erence only. They are attained at an engine speed of 1500 to 2000  
rpm and an ambient temperature of 20 °C after about 20 minutes.  
Refer to the vehicle-specific refrigerant circuit for the locations of  
the pressure gauge connections ⇒ Heating, air conditioning; Rep.  
gr. 87 ; Refrigerant circuit (vehicle-specific Workshop Manual).  
At 20 °C with the engine not running, the pressure in the refrig‐  
erant circuit is 4.7 bar ⇒ page 8 (vapour pressure table).  
Note  
Pressure can be measured in various units: 1 MPa (megapascal)  
is equivalent to 10 bar gauge pressure, or 145 psi; 1 bar absolute  
pressure is the same as 0 bar gauge pressure, which is roughly  
equivalent to atmospheric pressure.  
⇒ “3.8.1 Refrigerant circuit with expansion valve”, page 66  
⇒ “3.8.2 Refrigerant circuit with restrictor and reservoir”,  
page 68  
3.8.1  
Refrigerant circuit with expansion valve  
Note  
Only applies with restrictions to vehicles with an electrical air con‐  
ditioner compressor - V470- .  
HP – High-pressure side of refrigerant circuit (HD in illustration)  
LP – Low-pressure side of refrigerant circuit (ND in illustration)  
Component  
State of refrigerant  
Pressure (bar)  
Temperature in degrees  
centigrade  
-1- Evaporator, from inlet Vapour  
to outlet  
approx. 1.2 bar1)1  
approx. -7 °C 2)2  
-2- Expansion valve  
Liquid, expanded to va‐ approx. 14 bar  
approx. +55 °C (high-  
pressure side), reduced  
to -7 °C (low-pressure  
side)  
pour  
-3- High-pressure switch / Liquid  
high-pressure sender  
approx. 14 bar  
approx. +55 °C  
66  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Component  
State of refrigerant  
Liquid  
Pressure (bar)  
approx. 14 bar  
Temperature in degrees  
centigrade  
-4- Service connection  
(high-pressure side)  
and  
approx. +55 °C  
-5- Receiver  
-6- Condenser  
From gas (at inlet) via va‐ approx. 14 bar  
pour to liquid (at outlet)  
From approx. +65 °C (at  
inlet) to approx. +55 °C  
(at outlet)  
-7- High-pressure safety Gas  
valve  
approx. 14 bar  
approx. +65 °C  
and  
-8- Air conditioner com‐  
pressor (HP side)  
-9- Air conditioner com‐  
pressor (low-pressure  
side)  
Gas  
Gas  
approx. 1.2 bar1)1  
approx. 1.2 bar1)1  
approx. -1 °C 2)2  
approx. -1 °C 2)2  
-10- Damping chamber  
(not fitted on all vehicles)  
and  
-11- Service connection  
(low-pressure side)  
1) 1 - The pressure in a refrigerant circuit with a regulating air conditioner compressor is maintained at approx. 2 bar absolute (corresponding  
to approx. 1 bar gauge) despite varying heat transfer and fluctuating engine speeds. This applies however only within the rated range of  
the air conditioner compressor; if the rated range of the air conditioner compressor is exceeded, the pressure will increase  
⇒ page 193 .  
2) 2 - The temperature in a refrigerant circuit with a regulating air conditioner compressor is maintained within the regulating range of the  
air conditioner compressor despite varying heat transfer and fluctuating engine speeds. This however only applies within the output range  
of the air conditioner compressor. If the output limits of the air conditioner compressor are exceeded, the temperature will increase  
⇒ page 193 .  
Note  
♦ Non self-regulating air conditioner compressors are switched  
off by the relevant control unit via the air conditioner compres‐  
sor regulating valve - N280- at evaporator temperatures below  
0 °C.  
♦ On vehicles with air conditioner compressor regulating valve -  
N280- the pressure on the low pressure side is altered by  
actuating the valve.  
♦ On vehicles with two evaporators and two expansion valves,  
the temperature and the pressure in the refrigerant circuit cor‐  
respond to those on vehicles with only one evaporator and one  
expansion valve (parallel connection).  
♦ Depending on the version of the refrigerant circuit, a compo‐  
nent with internal heat exchanger may be fitted (e.g. a refrig‐  
erant line with internal heat exchanger is installed in the Audi  
A4 2008 > and in the Audi A5 Coupé 2008 >). In the internal  
heat exchanger, the hot refrigerant (liquid) flowing through the  
high-pressure side gives off energy to the cold refrigerant  
(gaseous or vaporous) flowing through the low-pressure side,  
thus enhancing the efficiency of the air conditioner  
⇒ page 44 .  
Arrows show direction of refrigerant flow.  
HP – High-pressure side of refrigerant circuit (HD in illustration)  
LP – Low-pressure side of refrigerant circuit (ND in illustration)  
3. General information on refrigerant circuit  
67  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
1 - Evaporator  
2 - Expansion valve  
3 - High-pressure switch / high-  
pressure sender  
❑ Different versions de‐  
pending on vehicle  
4 - Service connection (high-  
pressure side)  
5 - Receiver  
❑ Different versions de‐  
pending on vehicle  
6 - Condenser  
7 - High-pressure safety valve  
8 - Air conditioner compressor  
(high-pressure side)  
9 - Air conditioner compressor  
(low-pressure side)  
10 - Damping chamber  
❑ Not fitted on all vehicles  
11 - Service connection (low-  
pressure side)  
3.8.2  
Refrigerant circuit with restrictor and  
reservoir  
HP – High-pressure side of refrigerant circuit (HD in illustration)  
LP – Low-pressure side of refrigerant circuit (ND in illustration)  
Component  
State of refrigerant  
Gas  
Pressure (bar)  
Up to 20 bar  
Temperature in degrees  
centigrade  
-1- Air conditioner com‐  
pressor (high-pressure  
side)  
Up to +70 °C  
-2- Condenser  
From gas to vapour to liq‐ Up to 20 bar  
uid  
Up to +70 °C  
-3- Restrictor  
From liquid to vapour  
HP side up to 20 bar, LP HP end up to +60 °C LP  
side greater than 1.0 bar end warmer than -4 °C  
-4- Evaporator  
-5- Reservoir  
-6- Air conditioner com‐  
pressor (low-pressure  
side)  
From vapour to gas  
Gas  
Gas  
Greater than 1.0 bar  
Warmer than -4 °C  
The pressures on the low-pressure side are maintained at approx.  
2 bar absolute (corresponding to approx. 1 bar gauge) by the  
68  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
“regulating” air conditioner compressor even at varying engine  
speeds. This applies however only within the rated range of the  
air conditioner compressor ; if the rated range of the air condi‐  
tioner compressor is exceeded, the pressure will increase  
⇒ page 193 .  
Note  
On vehicles with air conditioner compressor regulating valve -  
N280- the pressure on the low pressure side is altered by actuat‐  
ing the valve.  
Arrows show direction of refrigerant flow.  
HP – High-pressure side of refrigerant circuit (HD in illustration)  
LP – Low-pressure side of refrigerant circuit (ND in illustration)  
1 - Air conditioner compressor  
(high-pressure side)  
2 - Condenser  
3 - Restrictor  
4 - Evaporator  
5 - Reservoir  
6 - Air conditioner compressor  
(low-pressure side)  
3. General information on refrigerant circuit  
69  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.9  
Tests and measurements performed  
with pressure gauge  
Pressure gauge scales  
1 - Temperature scale for refrigerant R134a CF3– CH2F or  
CH2F– CF3  
2 - Pressure scale  
Note  
Pressure can be measured in various units: 1 MPa (megapascal)  
is equivalent to 10 bar gauge pressure, or 145 psi; 1 bar absolute  
pressure is the same as 0 bar gauge pressure, which is roughly  
equivalent to atmospheric pressure.  
Pressure gauges may have one or more temperature scales in  
addition to the pressure scale. The scale values for R134a are  
assigned according to the vapour pressure table. As different re‐  
frigerants develop different vapour pressures at the same tem‐  
perature, there is a temperature scale for each refrigerant.  
⇒ “3.9.1 Tests and measurements which can be performed using  
pressure gauges”, page 70  
3.9.1  
Tests and measurements which can be  
performed using pressure gauges  
Refrigerant circuit pressure and temperature measurements  
♦ The high-pressure gauge measures the pressure and tem‐  
perature propagated evenly from the air conditioner compres‐  
sor outlet via the condenser to the constriction (restrictor or  
expansion valve) when the air conditioning system is switched  
on.  
♦ The low-pressure gauge measures the pressure and temper‐  
ature propagated evenly from the constriction (restrictor or  
expansion valve) via the evaporator to the inlet of the air con‐  
ditioner compressor when the air conditioning system is  
switched on.  
Note  
The relationship between pressure and temperature indicated on  
the pressure gauges only applies in a refrigerant circuit containing  
liquid or vapour, but not gas. In gaseous form, the temperature is  
approx. 10 °C to 30 °C higher than the pressure gauge reading.  
Detection of refrigerant in a closed vessel  
In a closed vessel or in the refrigerant circuit, refrigerant R134a  
is present if the temperature indicated on the pressure gauge  
corresponds to the temperature of the refrigerant (standing liquid  
assumes ambient temperature).  
A closed vessel or a deactivated refrigerant circuit is empty if the  
temperature indicated on the pressure gauge is below the tem‐  
perature of the refrigerant.  
70  
Rep. gr.87 - Air conditioning system  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
Note  
The relationship between pressure and temperature no longer  
applies if no liquid is present and f the pressure is only built up by  
gas.  
3.10  
Air conditioner service and recycling  
units  
Air conditioner service units for the extraction, cleaning and trans‐  
fer of refrigerant for motor vehicle air conditioning systems are  
currently available from various manufacturers.  
Only certain air conditioner service stations (with appropriate ad‐  
ditional equipment and various adapters if applicable) can be  
used for cleaning the refrigerant circuit (flushing it with refrigerant  
R134a) ⇒ page 100 .  
⇒ “3.10.1 Classification of extraction systems”, page 71  
⇒ “3.10.2 Charging systems that do not require a permit”,  
page 72  
3.10.1  
Classification of extraction systems  
WARNING  
When working on the refrigerant circuit and handling refriger‐  
ant, observe the generally valid safety precautions and pres‐  
sure vessel regulations.  
Note  
♦ The air conditioner service and recycling units used in motor  
vehicle workshops are extraction and charging systems that  
do not require a permit (Group “3”) but which should only be  
operated by qualified personnel. Instructions for the operation  
and service of the devices may be found in the respective  
manufacturer's documentation.  
♦ Extraction and charging systems of groups “1” and “2” are not  
used in motor vehicle workshops.  
Group “3” extraction and charging systems:  
Mobile extraction and charging systems for filling compressed-  
gas vessels permanently connected to the system  
The refrigerant or refrigerant/oil mixture is transferred to com‐  
pressed-gas vessels which are permanently connected to the  
mobile systems. In accordance with § 3 Para. 5 No. 3 of the Ger‐  
man pressure vessel regulations (different regulations may apply  
in other countries), compressed-gas vessels are classified as  
pressure vessels in this case.  
The charging systems:  
– Do not require a permit.  
– Do not require expert testing, as the gas is transferred to com‐  
pressed-gas vessels which are classed as being pressure  
vessels (On the other hand, a permit is required for the system  
to fill a pressurised gas container for transfer to another party  
from this pressurised container, and the permit requires an  
examination.)  
3. General information on refrigerant circuit  
71  
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...  
Air conditioner with refrigerant R134a - Edition 11.2018  
3.10.2  
Charging systems that do not require a  
permit  
WARNING  
When working on the refrigerant circuit and handling refriger‐  
ant, observe the generally valid safety precautions and pres‐  
sure vessel regulations.  
Charging systems not requiring a permit are ones used for trans‐  
ferring compressed gases to mobile compressed-gas vessels for  
internal use only.  
Note:  
Some air conditioner service units are charging systems not re‐  
quiring a permit. When working with such equipment, the refrig‐  
erant is not transferred to mobile compressed-gas vessels, but  
rather into a permanently installed charging cylinder with visible  
level gauge and float switch.  
Recommendation:  
It is advisable to use a portable cylinder with visible level gauge  
and high-pressure safety valve for surplus refrigerant for internal  
use.  
Various technical regulations (e.g. TRGS 400, TRGS 402, TRGS  
407, TRGS 510, TRGS 725/TRBS 3145) must be noted when  
filling compressed gases into other compressed-gas vessels.  
3.11  
Repair notes for refrigerant circuit  
WARNING  
♦ When working on the refrigerant circuit, observe generally  
valid safety precautions and pressure vessel regulations.  
Special tools and accessories:  
The performance of proper workmanlike repairs on an air condi‐  
tioning system  
•
•
•
Requires the use of special tools and materials as listed on  
⇒ page 377 .  
Requires compliance with the basic instructions for use of leak  
detectors ⇒ page 169 .  
Requires expert knowledge.  
Note  
Releasing refrigerant into the environment is prohibited  
⇒ page 73 (laws and regulations).  
72  
Rep. gr.87 - Air conditioning system  

Related Topics

Components of refrigerant circuit
Layout of components of refrigerant circuit and their influence on high-pressure and low pressure sides
Design of refrigerant circuit
Refrigerant circuit with electrically driven air conditioner compressor
Connections for quick-release coupling in refrigerant circuit
Switches and senders in refrigerant circuit and related connections
Electrical components not installed in refrigerant circuit
Pressures and temperatures in refrigerant circuit
Tests and measurements performed with pressure gauge
Air conditioner service and recycling units
Repair notes for refrigerant circuit

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