Get General information on refrigerant circuit -> Switches and senders in refrigerant circuit and related connections Guide for 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

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

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

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