Replacing Air Con Compressor on 2002 Audi Allroad 2.5TDI AE

Hi. I am in the middle of replacing cambelt, water pump, pulleys, tensioners etc. and have discovered the tensioner for the air con compressor is shattered (belt also shredded). The
tensioner and two idler pulleys on the main v-belt are pretty knackered also! Fortunately, I have planned replacing all of these in this job. However, although the compressor is not
seized, the electro mangentic coupler and the belt pulley on the compressor seem a bit rough also. Looking at the cost of replacing these, it seems it would be wise to replace
the full compressor.
The above has come as a bit of a surprise and I have not boned up on how the air-con system works. I have the compressor off at present (have today just replaced the mounting bushes on the power steering bracket). So I need to know what is involved in replacing with a new compressor - In particular,

1) I assume if I detach the two pipes from the old one and attach to a new one, I will have to get the refrigerent re-charged, yes?? If so, can QuickFit or whoever do the recharging or do I need to visit the Audi dealer?

2) Anything to be mindful of when detaching the two pipes?

3) From reading the manual, I first have to drain the oil from the old one - to measure the amount that was in it and then I empty the new one and refill again with this amount. Is this correct?

Any thing else involved in the replacement? As I will be in the south of France for the summer I need to ensure the aircon if fully functional. Once again, all comments appreciated.

If you disconnect the compressor without having the system degassed you risk serious refrigerant burns and you are releasing unpleasant gases.

These are the Audi notes on your system.

Safety precautions when working on vehicles with air conditioners and when handling refrigerant

The assemblies and pipes in the air conditioner are filled with refrigerant 1.1.1.2 Tetrafluorethane (CF3-CH2F or CH2F-CF3).

This refrigerant is currently known in Germany by the trade names R134a, H-FKW 134a, SUVA 134a and KLEA 134a (other trade names may be used in other countries).

Safety precautions

The following precautions should be observed with this refrigerant in Germany (additional regulations may be applicable in other countries).
If it is necessary to open the refrigerant circuit during repair work, first drain the refrigerant circuit making sure to avoid all contact with liquid refrigerant or refrigerant vapours. If, despite the observance of the safety precautions, refrigerant should escape, the refrigerant/air mixture must not be inhaled.
For this reason, always switch on the extractor systems, and protect hands with gloves and eyes with safety goggles.

Reason:

The intensive action of refrigerants will cause frostbite on unprotected parts of the body.

Important:

If, despite observance of all the security precautions, refrigerant should come into contact with other parts of the body, they should also be thoroughly rinsed immediately for at least 15 minutes in cold water.
Although refrigerants do not represent a fire hazard, smoking, welding, soldering and brazing are not permitted in areas exposed to refrigerant.

Reason:

The high temperature of a naked flame or hot objects causes refrigerant gas to undergo chemical decomposition. The inhalation of the toxic decomposition products results in dry coughing and nausea.

Draining the refrigerant circuit

Refrigerant must not be allowed to escape into the environment, it should be extracted from the refrigerant circuit by means of a suction unit or service station. The extracted refrigerant is then reprocessed on site or returned to the manufacturer for environmentally friendly disposal (in other countries, different or additional regulations may apply). For this reason, the vehicle should be handed over to an air conditioning servicing centre (these workshops have the relevant equipment and tools).

Reason:

Escaped refrigerant R134a in the earth's atmosphere aggravates the greenhouse effect.

Notes:

◆ The greenhouse effect of refrigerant R134a is much less than that of refrigerant R12.
◆ The refrigerant R134a does not affect the ozone layer in the earth's atmosphere (R134a is an H-FC with no chlorine atoms). The depletion of the ozone in the upper atmosphere is only caused by the splitting of carbon-chlorine bonds (as is the case, for example, with the refrigerant R12).

After draining the air conditioner, disconnect the voltage supply to the magnetic clutch -N25 or the regulating valve -N280. Depending on the vehicle version, remove the connector from the air conditioner pressure switch -F129/high-pressure sender -G65 or unplug the connector at the compressor (to the -N25/-N280).

Reason:

Disconnecting the voltage supply ensures that the compressor cannot be switched on by mistake via the magnetic clutch -N25 while the refrigerant circuit is empty.
The regulating valve -N280 is no longer actuated and the compressor is idling. This compressor is designed so that during idling the compressor's components are lubricated via an internal oil circuit (until there is sufficient refrigerant in the compressor).

Working on the refrigerant circuit

Work on the refrigerant circuit must only be performed in well ventilated rooms. Care should be taken to ensure that there are no inspection pits, shafts or cellar entrances within a radius of 5 metres. Switch on the extraction systems.

Reason:

Escaping refrigerant is not only colourless and odourless, but also heavier than air and therefore displaces oxygen. If, despite the observance of all the safety precautions, refrigerant gas is emitted, there may be a negligible risk of asphyxiation in poorly ventilated rooms and workshop pits.

Note:

The mixture of gas and air which forms when refrigerant gas escapes must not be inhaled; it must be extracted using suitable extraction systems (workshop extractor).

Welding, brazing and soldering must not be performed on parts of the filled air conditioner. The same applies to welding and soldering work on the vehicle if there is a risk that parts of the air conditioner could become warm.

Reason:

The application of heat creates a severe build-up of pressure in the system which could cause it to burst.

Remedy:

Drain the refrigerant circuit

Note:

Damaged or leaking parts of the air conditioner may not be repaired by welding or soldering; they should be renewed instead.
During repair work on the air conditioner, all open components and pipe connections in the air conditioner should be re-sealed immediately.

Reason:

Air conditioner components left open for a lengthy period present a risk of moisture penetration. Air conditioners which have been left open for a lengthy period cannot, therefore, be re-filled without replacing parts of the system.
Painting work on vehicles with air conditioner

When carrying out paintwork repairs, ensure that the vehicle is not exposed to temperatures of more than 80 °C in the drying ovens or their preheating zones.

Reason:

The application of heat creates a severe build-up of pressure in the system which could cause it to burst.

Crasher, many thanks for the detailled info. I did not have the time to plough thru the manual. Again, I would be grateful if you have any comments on the following intended course of action:
1) I will try to get replacement part no 42Z260811 (ie coupler & pulley) and fit these as per the manual.
2) If I cannot source the above or too costly, I will reinstall the original compressor and, assuming it is still functioning ok, run with it until I have a problem (By easy under-car inspection I can keep an eye on the pulley and belt condition).
3)If compressor fails or when I get round to replacing with a new one, I will first get Audi dealer (has to be Audi??) to evacuate the system. I will then install (safely now - yes?) the new compressor and then return to dealer to have refrigerant re-charged.
Does this seem a sound plan?
Thanks again for your support on this.

No need for the dealer to drain the system, there are plenty of places that can do this, some mobile. Some will even wait whilst you quickly plumb up the new compressor and then re-charge the system.