Get Refrigerant circuit -> Blowing out refrigerant circuit with compressed air and nitrogen 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

Caution

♦ Observe the applicable regulations, technical rules and

laws when charging recycling cylinders (compressed gas

cylinders).

♦ Recycling cylinders must never be overfilled. If recycling

cylinders are overfilled, the gas cushion is too small to

withstand the expansion of liquid caused by exposure to

heat. There is a risk of bursting.

♦ For your own safety, only use recycling cylinders with a

built-in safety valve.

♦ Recycling cylinders must be weighed on calibrated scales

during the filling process. The maximum permissible ca‐

pacity is 75% (filling factor 0.75) of the filling weight indi‐

cated on the recycling cylinder (the possibility of refriger‐

ant oil entering the recycling cylinder along with the

refrigerant cannot be ruled out).

5.4

Blowing out refrigerant circuit with com‐

pressed air and nitrogen

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.

5. Refrigerant circuit

95

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

– 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 ; Battery; Charging

battery and ⇒ Electrical system; Rep. gr. 93 ; General warning

instructions for work on the high-voltage system .

– 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.

Note

♦ Move the selector lever to position “P” and activate the parking

brake before performing test and measurement work for which

the ignition must be switched on but where the vehicle's drive

system does not need to be active.

♦ The status of the drive system (READY) is shown by the con‐

trol unit in dash panel insert - J285- via the “power meter” ⇒

Owner's Manual .

♦ Activating and deactivating drive system ⇒ Owner's Manual

(note display of control unit in dash panel insert - J285- ).

All vehicles

The best way of removing moisture, impurities and old refrigerant

oil from the refrigerant circuit without any unnecessary loss of re‐

frigerant and without extensive assembly work, whilst at the same

time ensuring environmental compatibility, is to clean (flush) the

refrigerant circuit with refrigerant R134a or to blow it out with

compressed air and nitrogen.

96

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

♦ Blowing out the refrigerant circuit with compressed air and ni‐

trogen usually involves far more work than cleaning (flushing)

with refrigerant R134a. Cleaning (flushing) with refrigerant

R134a also provides far better cleaning of the components.

Flushing should therefore always be employed in the event of

complaints (blowing out should only be applied when dealing

with certain problems and for particular components).

♦ Under certain conditions it may, for example, be sufficient to

blow out specific components (e.g. individual refrigerant pipes

or refrigerant hoses) with compressed air and nitrogen (for in‐

stance to force old refrigerant oil out of individual components

following removal).

♦ Certain impurities are impossible or difficult to remove properly

from the refrigerant circuit using compressed air. Such impur‐

ities can be removed for example by cleaning (flushing) with

refrigerant R134a ⇒ page 100 .

♦ A maximum working pressure of 15 bar is not to be exceeded

when blowing out (corresponds to the pressure prevailing in a

charged refrigerant circuit at an ambient temperature of ap‐

prox. 60 °C; use pressure reducer for compressed air as well

if applicable).

WARNING

♦ There may be an uncontrolled flow of nitrogen out of the

cylinder.

♦ Only use pressure reducer for nitrogen cylinders (max.

working pressure 15 bar).

♦ Use appropriate extraction units to draw off the gas mix‐

ture escaping from the components.

– Always flush or blow out components in direction opposite to

refrigerant flow.

Note

The restrictor, expansion valve, air conditioner compressor, re‐

ceiver and reservoir cannot be flushed with compressed air and

nitrogen.

– In the case of condensers fitted with a desiccant cartridge in

the integrated receiver, this cartridge is to be removed.

Note

♦ On vehicles with condensers with an integrated receiver/des‐

iccant cartridge which cannot be renewed separately, the

condenser must be renewed after it has been cleaned (flush‐

ed).

♦ Depending on the version, receivers on which the desiccant

cartridge can be renewed separately may be provided with an

additional filter element which may have to be renewed to‐

gether with the desiccant cartridge.

5. Refrigerant circuit

97

Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A1 Sportback 2 ...

Air conditioner with refrigerant R134a - Edition 11.2018

– First flush out the old refrigerant oil and dirt with compressed

air and then use nitrogen to remove the moisture from the

components.

– For adapter for connecting pressure hose to refrigerant circuit,

refer to ⇒ page 187 .

Observe the following to prevent oil and moisture from the com‐

pressed-air system from entering the refrigerant circuit.

– The compressed air must be passed through a compressed-

air purifier to clean and dry it. Use is therefore to be made of

filter and dryer for compressed air (included in scope of deliv‐

ery as tool for painting work).

– For refrigerant lines with thread or union nut at connection, use

adapters from adapter set - V.A.G 1785- ( adapter - V.A.G

1785/1- to adapter - V.A.G 1785/8- ) for connecting 5/8" -18

UNF filler hoses (some of these adapters are also contained

in the adapter set for refrigerant circuits - VAS 6338/1- ).

– For refrigerant lines with no thread or union nut at connection

(for connecting adapters), use adapters from adapter set for

refrigerant circuits - VAS 6338/1- or commercially available

blow-out gun with rubber mouthpiece.

Note

♦ The refrigerant circuit is only to be blown out with compressed

air and then nitrogen if no means of cleaning (flushing) the

refrigerant circuit with refrigerant R134a are available or if

flushing of individual components would involve too much

work (blowing minor impurities and small quantities of mois‐

ture out of refrigerant pipes for example is not particularly time-

consuming).

♦ Compressed air/nitrogen emerging from components must be

drawn off using an appropriate system (e.g. workshop extrac‐

tor).

The refrigerant circuit (or individual components) is/are to be

blown out if no means of cleaning (flushing with refrigerant

R134a) are available or if cleaning (flushing with refrigerant

R134a) seems inappropriate

– In the event of dirt or other impurities in individual circuit com‐

ponents

– If vacuum reading is not maintained on evacuating a leak-free

refrigerant circuit (pressure build-up due to moisture in refrig‐

erant circuit)

– If the refrigerant circuit has been left open for longer than the

normal assembly time (e.g. following an accident).

– If pressure and temperature measurements in the refrigerant

circuit indicate that there is moisture in the circuit.

– If it is uncertain how much refrigerant oil is in the refrigerant

circuit.

– If the air conditioner compressor has to be renewed on ac‐

count of internal damage (e.g. noise or no output).

98

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

For vehicles with an electrically driven air conditioner compressor,

see the notes on renewing the electrical air conditioner compres‐

sor - V470- (damage to the air conditioner compressor electronics

does not always mean that the refrigerant circuit has to be

cleaned) ⇒ page 277

– If stipulated by the vehicle-specific Workshop Manual after re‐

newing certain components

Note

Certain impurities and old refrigerant oil are impossible or difficult

to remove properly from the refrigerant circuit using compressed

air. Such impurities can be removed for example by cleaning

(flushing) with refrigerant R134a ⇒ page 100 .

⇒ “5.4.1 Blowing out refrigerant circuit”, page 99

5.4.1

Blowing out refrigerant circuit

Note

♦ In the case of vehicles on which the refrigerant lines have no

threads for connection of adapters V.A.G - 1785- , use is to be

made, for example, for blowing out the individual components

of a blow-out gun with rubber mouthpiece or an adapter from

the VW/Audi passenger vehicle adapter set - VAS 6338/1- .

Take special care not to damage the connections by crushing

or scratching them when using an air pistol with a rubber end

piece.

♦ The evaporator must be blown out via the connection for the

low-pressure line (large diameter) after removing the expan‐

sion valve or restrictor.

♦ Always clean (flush or blow out) components in the opposite

direction to the refrigerant flow.

♦ Check expansion valve and renew if dirty or corroded.

♦ If dark, sticky deposits cannot be removed with compressed

air, clean (flush) the components concerned with refrigerant

R134a or renew.

♦ Thin, light grey deposits on the insides of pipes do not impair

the function of the components.

♦ After flushing, always renew receiver or reservoir and restric‐

tor. In the case of condensers fitted with a desiccant cartridge

in the integrated receiver, this cartridge must be renewed.

♦ On vehicles with condensers with an integrated receiver/des‐

iccant cartridge which cannot be renewed separately or which

are not available as a replacement part, the condenser must

be renewed after cleaning (flushing) ⇒ Electronic parts cata‐

logue and ⇒ Heating, air conditioning; Rep. gr. 87 ; Refriger‐

ant circuit (vehicle-specific Workshop Manual).

♦ Depending on the version, receivers on which the desiccant

cartridge can be renewed separately may be provided with an

additional filter element which may have to be renewed to‐

gether with the desiccant cartridge.

5. Refrigerant circuit

99

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Refrigerant circuit -> Blowing out refrigerant circuit with compressed air and nitrogen for Your Audi A2 SUV 1999-2005

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