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leeds lad
10-07-2017, 10:50 PM
I hope I have posted in the right place - can someone move it if not
I have a 2011 Golf 1.6 tdi. The aircon doesnt work and there are no fault codes in 08 or any of the other systems (apart from 'control for signal Horn 009 - open or short to ground)

So I have compared the vacom measuring values with an identical car who's aircon works fine. When the engine is started the gas pressure raises (over a few minutes) from 5.2 bar to 10 bar and the 'temp after the evaporator' reduces from about 24 deg down to 5 deg


The air con that doesnt work has a gas pressure of about 6 bar and raises to 7 bar over the same time) and the 'temp after evaporator' stays about constant hence not cooling.


The 'compressor load' is about the same on tickover and reduces by about the same amount on both cars as the revs are raised to 1800 rpm -starts about 2.2 nm reducing to about 1.5 nm probably a little bit lower on the car that is working but I put that down to there being a bit less gas in that one.
Am I right in thinking that if the 'expansion Valve' is stuck open or partially open there will be no differential in gas pressure and no cooling plus would this prevent the gas pressure rising as the compressor has little resistance to work against?
in my head the compressor is increasing the gas pressure a small amount so must be working at least a bit - do they usuall fail completely or just start to go week?
Would a faulty compressor have the same effect and is there anything that I should be looking for on vagom that gives an indication of whether the fault is in the expansion valve or the compressor. The problem is the compressor is dear and I dont want to waste my money if its not the compressor. - were they as till as problematic in 2011 as earlier models?
Thanks for any input

Rob69
11-07-2017, 06:54 AM
If it is not a problem with the air mixing flaps, (no fault codes and you can hear the motor working?) I think you have gas in the system as seen by your pressure indications, but have lost some of your charge over the last 6 years or so ( unless it has been regassed) and you have little or no liquid level in the condensor/ filter drier with which to expand, evaporate and provide the cooling. I don't know how accurate those compressor load readings actually are. I'd suggest for what it costs, you go and get a regas done.

FLAPPERJACK76
11-07-2017, 08:18 AM
Go to 08 heating and ac .measured value 1 field 1 . What have you got?

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Crasher
11-07-2017, 10:17 AM
The data is easy, no codes, good pressure, no chill, new compressor or modulation valve.

leeds lad
12-07-2017, 06:01 PM
Thanks Crasher I've ordered a compressor (ill let you know how I go on) - Just so that I know, does the compressor shaft turn permanently and then the Modulator valve controls when the refrigerant flow so there is no need for a clutch or have I got it wrong?

Crasher
12-07-2017, 06:37 PM
Yes it is a constant drive modulated delivery unit, it is usually the modulator that fails but I prefer just to fit a top quality new compressor.

leeds lad
12-07-2017, 10:04 PM
My compressor part number is 5N0820803A Delphi
What is the difference between the compressors that have a different letter at the end? If when mine turns up it has a different letter does it matter?