climate control failure - NOT compressor

Hi there - not too sure where to post this - please move this if it's in the wrong place!

My A2 is nearly 7 years old. no problems with the climate control until just a few months ago. I had hot air but no cold air but as it was winter - didn't matter too much (although I wasn't happy when the windows kept misting......). I have the climate control running always. Anyway - had the system re-gassed but that didn't solve the problem. So last week - an air-con specialist (it's all he does!) emptied the gas, refilled it, had a think and then said it was the compressor. So a new one from Audi was ordered and fitted. However - this has not solved the problem 'cos the climate control is still not working. The chap mentioned that the new compressors from Audi are now fitted with microchips and possibly my car cannot read this (newer) chip hence the problem. He is saying that he will now connect back my old compressor and I should go to Audi themselves to get the problem sorted. Please can anybody shed here shed some light on this?

I am in Liverpool, if that's any help and my A2 is 1.4SE petrol

This seems to be a sensor problem which is quite common. You could have asked for an electronic diagnostics before doing all the compressor work and re-gas. Diagnostics should return some fault codes that tells you what's wrong. Spike had the G263 evaporative temperature sender failure, so have I. When it fails, the compressor doesn't run properly.

So I would suggest you ask a VW/Audi garage or dealer with VAG-COM or VAS 5052 to check your car. Get the fault codes, ask for a quote. Come back and post here what's the problem because with A2OC members can give you very good advice on what to do next.

Thank you for your reply, humps! I will do what you have suggested and get back to you.

Back again!

What a saga this is turning out to be. The new compressor did not solve the problem and it's been checked that it is not faulty itself. So have had the car diagnosed (not by Audi!) and the code is DTC 796???? Anyway - apparently it appears to be the blower temperature sender. The air-con chap said to go back to Audi and get it sorted there. Called Audi who said that they have to diagnose it themselves (which will cost £55 plus VAT) 'cos the fault could be anything. Hmmmm!

I am told that a sender could cost about £200?

Hubby has now instructed air-con man to replace the new compressor with the original one whilst we think about waht to do next.

Now thinking is it worth getting it fixed? After all - the car is 7 years old - just a shame that the climate control is not working.

Hi Jools, don't despair, I'm in the same boat, my AC is not running and still trying to find out what's wrong and my car isn't new, 2001 Y but I like it a lot. Google says your fault code is 00796 Fan for Integer Temperature Sensor -V42. I can have a look tonight when I get home.

You dealer is not wrong in saying the fault code could be anything. It indicates a particular component isn't right but it could be anything from a loose wire to a broken sensor. The sensor should cost less than £20, the rest of the £200 will be labour and diagnostics.

There are many reasons why A/C is not switched on, or running at limited capacity. If the sensor is accessible, DIY-ing is possible. I'll check tonite or other members will be able to help Meanwhile, something you can check.
Switch ECON ON and turn tempreature down to LO, feel the temperature at the vent by hand or thermometer.
Switch ECON OFF and feel if there is any difference in temperature (give it a good minute or so)

There is a difference between A/C at limited capacity or not at all.

Got the same problem over here, got it regassed but nothing, so bought a new compressor but still need to get it fitted, so will see what happens!

Humps - have done what you said and cannot feel any difference in the temperature.

Air Con service

Last time I was in my local Audi Stealer, they had loads of leaflets on
the service desk offering a full Air Con service for £99.00 incl VAT.

What they mean by full, I don't know. I guess any parts required would
be extra, but does it include topping up the gas???
I should have read the leaflet!

jools, that means your compressor is not running at all. According to your given fault code 00796, it is the -V42 sensor. This should be the round blower component at the top of your climate control panel. I don't see a part number for it and it may mean a replacement of the whole control panel itself. However, the workshop manual doesn't say if v42 failure will result in the compressor completely switched off. Anyone else knows?

As a suggestion, take the panel out, with all wires still connected check that the blower spins when CC is on. It could be just the blower motor is dead (as opposed to sensor broken). Still, not sure what can be fixed but that's what the fault code indicates.

If I remember, I had once quoted by dealer the CC unit is over £400. So your dealer quote parts and labour for £200 seems a great deal! But assuming that IS the actual problem and they're not coming back to blackmail you AFTER the initial diagnostics. If you can find a working panel, swap it in to verify it is the actual problem. Your local breaker or ebay!

GBMSU said:

Last time I was in my local Audi Stealer, they had loads of leaflets on
the service desk offering a full Air Con service for £99.00 incl VAT.

What they mean by full, I don't know. I guess any parts required would
be extra, but does it include topping up the gas???
I should have read the leaflet!

Click to expand...

Best is to ask the dealer what's included. I went to a VAG specialist who charged just under £70 inc. vat for full a/c servicer. That includes regas, new pollon filter and checks. Well, obviously the cheks failed as they didn't spot the a/c wasn't even running after the service!

Just to reinforce what humps said earlier, a diagnostic scan should be the first step in troubleshooting aircon problems on the A2.
This is an extract from a mail written in 2007

''Hi A2return2
Think I mentioned this earlier but I highly recommend you have a diagnostic scan done before paying out for a new aircon compressor. Temperaure and pressure sensors in the system control how hard the compressor works so just one faulty sensor could virtually shut down the compressor. Sorry to say that most aircon 'specialists' probably have no experience on the variable displacement compressor used on our A2's''

Cheers Spike

A bit left field, but my a/c has failed twice in the last year or so. 54 reg, 72k miles. Both times the diagnosis has been a faulty a/c compressor drive pulley.

I'm not sure what could fail (may include the clutch?), and it may be nothing to do with your issue, but I just wanted to drop it into this thread of "a/c failure, not compressor".

Alan

wise words from Spike as always and thanks for Alan's note as well.

As for my own a/c not running, I'm running out of options. Gas - checked. Swapped in another CC panel - done that. Sarge helped me with the scan and no obviously problems. G263 - replaced and I even measured the old vs new temperature probe and found it is not the problem.

The speed of the compressor is driven by the frequency of the +ve pulse given to the two wire connector. I don't have an occiliscope but I suppose any +ve voltage reading on a std multimeter will mean CC panel is telling the compressor to work. That should rule out electronics and sensors. I would then look into the compressor or the pulley. If reading is v. low or zero, it is back to electronics. Question is, how do I access the compressor's connector? Axel stands and take the under tray out? Any have a photo?

alanb said:

A bit left field, but my a/c has failed twice in the last year or so. 54 reg, 72k miles. Both times the diagnosis has been a faulty a/c compressor drive pulley.

I'm not sure what could fail (may include the clutch?), and it may be nothing to do with your issue, but I just wanted to drop it into this thread of "a/c failure, not compressor".

Alan

Click to expand...

Hi Alan

The A2 does not have a magnetic clutch within the drive pulley like most other cars. On our A2's the aircon compressor is driven all the time with the variable displacement pumping elements giving between 2% and maximum flow depending the demands of the system.
To prevent mechanical damage to the compressor unit or failure of the drive belt under sever load the pulley has rubber elements which deform and allow the pulley to freewheel on the compressor shaft. I suspect the rubbers do not recover so the pulley must need replacing if this occurs.

Cheers Spike

spike said:

Hi Alan

The A2 does not have a magnetic clutch within the drive pulley like most other cars. On our A2's the aircon compressor is driven all the time with the variable displacement pumping elements giving between 2% and maximum flow depending the demands of the system.
To prevent mechanical damage to the compressor unit or failure of the drive belt under sever load the pulley has rubber elements which deform and allow the pulley to freewheel on the compressor shaft. I suspect the rubbers do not recover so the pulley must need replacing if this occurs.

Cheers Spike

Click to expand...

Spike

Thank you for that. Most helpful to clarify what has been going on.

Alan

Just a little update so other members with air con problems may follow some tests that I did. After making sure there is no more fault codes coming out of a VAG-COM scan, I turned to ElsaWin workshop manual. In Heating, Air-conditioning section. Read the electrical diagnostics, then got out a multimeter!

I briefly tested the refrigerrant from the service holes so I skipped the pressure signal test. I went straight for the compressor, or what they call the N280 regulating valve. Locate the two wire connector plug to the compressor (bottom of engine). By unclipping the lower front grill, I can reach the plug directly through where TDIs have their intercooler TDI owners will need arm of a monkey or axel stand and reach from bottom after removing the undertray.

I used two automotive wire crimps to attach two free running wires to my multimeter, otherwise you need the VAG test harness. Start engine, climate set to LO and ECON off. Measure the voltage and aim for roughly battery voltage (12V). I got unsteady reading of <300mV while ECON mode either on/off. So this is could be a short or compressor valve. Stop engine and unplugged the connector. Restart the test across the plug unconnected. I got close to battery voltage with ECON on or off(~10V). So I think this is compressor valve issue. For good measure, I opened the 12pin connector behind the CC panel. Measured the voltage on pin 3/4 across earth. I got reading but not quite battery voltage. Still, I don't think it is a short or electrical issue. New compressor it is then!

Anyone know rougly how much it is? Elsawin says compressor can be replaced without draining the refrigerant but then it also says take it to an air-con specialist!? I doubt I can replace it myself though.

The price for a new, from a dealer, refrigerant compressor is:

Are you sitting down?































£497.64!!

Ouch!

Cheers,

Mike

I sat down and has fallen off my chair with my jaws dropped...

hey, so i got a compressor from the breakers, fixed it up and ac was working, but radiator fan wasnt spinning, so traced it back and found fuse was blown, so thought lets connect the wires just to see...connected and smoke started coming out the central unit, turned out that was faulty, so changed that and now radiator fan is spinning and cold air is blowing all in time for summer

I've had a a/c problem since i bought my car a year ago it is Y reg but the strange thing is the a/c works once in a blue moon. We have it set at lo at the moment and some days "rarely" it will just start working we can tell this as it smells funny in the car and obviously gets colder. I have had the A/C re-gassed from kwik-fit as they are the cheapest i have found and local. I have also vag-com checked the car but am not getting any fault codes except a central convenience Faulty message????????? could this cause the problems i am happing, i have read they a prone to failure in early A2 does any one know the part no of the revised central convenience for a 2001 A2??