Audi a4 Air Con not cold....

REDLAD123 · 17-07-2012 8:03pm #1

Guys my 2002 Audi a4 1.9 TDi is not blowing cold air when the the temp is turned down to "Low" on the instrument panel.
I bought a re-fill can from a motor factors but when I connected it to the system the little guage on the re-fill can indicated the system was already "filled" (so I did not use the re-fill can and got my money back thankfully...)
I have checked the fuses and they are fine.
The ECON light is not staying on or anything. The panel is working fine, its just not blowing out cold air.
Does anyone know how to check if the compressor/ compressor clutch is working on my car? I've tried turning the aircon on while the car is running but I dont notice any change... I connected my VAGCOM to the car but I'm only getting the "Controller not Responding" error..
Is there anything else I can try?

firefly08 · 17-07-2012 8:33pm

Firstly, you were right to bring back the recharge kit - they're not ideal unless you know for a fact that the problem is low refrigerant and you know it's a very slow leak. The gauge tells you the pressure on the low side only which is not really enough info.

To see if the compressor/clutch is working: look at the front of the compressor - you should see the part in front of the pulley not turning when ac is off. When the ac is on, the part in front turns with the pulley. You have to be able to see it to know for sure.

If it's not switching on, find out where the relay is (I'm not sure) and listen for the click when you turn the ac on. Pull the relay and test it if you're not sure. If the relay is activating and the clutch still doesn't engage, the wiring to the clutch could be bad - if not, the clutch could be shot. There is a low pressure cut off switch that stops the compressor from engaging if the refrigerant pressure is too low, but if your gauge showed normal pressure then that's probably not it.

If the clutch is coming on and you're still not getting cold air, you might still be low on refrigerant - a good sign would be "short cycling" where it switches on and off frequently. Only a proper manifold gauge that reads both high and low sides will tell you if the pressures are right. But the pressure doesn't drop until the system is almost empty - so you can have low enough refrigerant to result in no cold air and still not see anything wrong with the pressure...that's where the short cycling helps to indicate the problem.

If pressures are good and the compressor is not short cycling...then I don't know sorry

AC is complicated and you need a specialist

REDLAD123 · 17-07-2012 8:50pm

I'll try that now and reply with my findings.. Thank you :cool:

firefly08 · 17-07-2012 8:58pm

No worries, one other thing - the oil that lubricates the compressor is mixed up with the refrigerant - so low refrigerant = low compressor oil...you don't want to run the compressor any longer than you need to for diagnosis.

REDLAD123 · 17-07-2012 9:57pm

I just had a look to see ifI could try find the compressor. I think I found it but access is very limited so I cannot see the front of the pulley at all. When I swich the aircon on there is a definite noise of another fan coming on but it seems to be between the dash and bulkhead. I'm not sure what to do next as I am unable to determine if the clutch on the compressor is operational

firefly08 · 17-07-2012 10:14pm

You don't need to be able to see the face of the pulley, just the bit that protrudes past the belt if you follow me.

If you're not 100% sure you found it...I don't know where it's located on that engine...but they typically look a little bit like an alternator. Similar size to the alternator and usually driven by the same belt. Can you see all the pulleys that are driven by the belt? If so, it has to be one of those. Rule out the alternator and power steering pump if you know what they look like - that should leave only the tensioner and the ac compressor I think.

Can you see a pair of aluminium pipes going from the firewall, towards the front of the engine and down into the depths? That is what air conditioning lines typically look like - try to trace them to a yoke with a pulley on it. Also, can you trace the lines from the condenser? That'll be a radiator - smaller than the engine radiator but mounted in the same place, probably in front.

The pulley itself looks distinct because it has the magnetic clutch in front of the actual pulley - it'll be the only pulley that has that, but it can be hard to see. Shine a light on them with the engine idling and ac off- if one pulley has a bit sticking out in front that's not turning, that's it.

REDLAD123 · 17-07-2012 10:31pm

Brilliant. Ya I think im looking at the right one from your description. I'll have a look in the morning again as its too dark now to do anything. Thanks again for your help..

carbon nanotube · 17-07-2012 10:47pm

the clutch is the main thing to check.

if it doesnt click, you can check the compressor fuses and relay.

if you know what you are doing there's an easy test to rule out the compressor by putting 12v directly from the fuse box into the car battery. (from the compressor relay)

it should click, but dont hold the wire too long... might melt

if the clutch clicks could be a sensor or low ac gas.

or even more a bust ac radiator.

my bet is the clutch given the year of the car and that fact people generally don't use AC as much as they should, the clutch needs action, it loves getting some cold ac into the cabin. it hates being left alone and used..

REDLAD123 · 18-07-2012 8:29am

carbon nanotube wrote: »

the clutch is the main thing to check.

if it doesnt click, you can check the compressor fuses and relay.

if you know what you are doing there's an easy test to rule out the compressor by putting 12v directly from the fuse box into the car battery. (from the compressor relay)

it should click, but dont hold the wire too long... might melt

if the clutch clicks could be a sensor or low ac gas.

or even more a bust ac radiator.

my bet is the clutch given the year of the car and that fact people generally don't use AC as much as they should, the clutch needs action, it loves getting some cold ac into the cabin. it hates being left alone and used..

Interesting. Where would I find the relay? I know a bit about cars but I've never done a test like that (I've very little knowedge of car electrics) I would assume it would be in the engine bay? The fusebox itself has no relays in it anyways.
Thanks for your input..

carbon nanotube · 18-07-2012 11:38pm

use google.

get a wire, doesnt have to be huge use a 2 core one from a mains or something and double it up.

tap the relay of the compressor and hook it to battery +

compressor should click... thats assuming the fuse is good.

dont hold the wire long.

also the relay itself could be bad, you can put 12v across the relay from the battery to see if it clicks.

firefly08 · 19-07-2012 5:54am

While that is all true (you can find out how to test a the clutch and relay on youtube in more detail) I still think you should keep looking until you can see if the compressor is turning or not...I am sure there must be a way you can see it. Knowing this will simplify life because if the compressor won't engage, then you can start tinkering with relays etc. but if it is engaging, and your cabin blower is working, and you're still not getting cold air, then you know it's something you can't fix yourself.

Here is a video that shows what you're looking for http://www.youtube.com/watch?v=vDIwq8JrAfQ

I realize you don't have that much clearance in the Audi to see it from that angle, but if you look closely you'll see that everything forward of the pulley turns, so you can tell just by looking down on it from the top...you might just have to shine a torch on it when it's stationary to see some detail that you can focus on...if that makes sense.

firefly08 · 19-07-2012 6:02am

OK I just ran out and snapped a quick pic of mine...this is an Audi A6 petrol model...the AC pulley is right down at the bottom, circled in red:

attachment.php?attachmentid=213806&stc=1&d=1342674056

attachment.php?attachmentid=213806&stc=1&d=1342674056

carbon nanotube · 19-07-2012 11:12pm

firefly08 wrote: »

While that is all true (you can find out how to test a the clutch and relay on youtube in more detail) I still think you should keep looking until you can see if the compressor is turning or not...I am sure there must be a way you can see it. Knowing this will simplify life because if the compressor won't engage, then you can start tinkering with relays etc. but if it is engaging, and your cabin blower is working, and you're still not getting cold air, then you know it's something you can't fix yourself.

Here is a video that shows what you're looking for http://www.youtube.com/watch?v=vDIwq8JrAfQ

I realize you don't have that much clearance in the Audi to see it from that angle, but if you look closely you'll see that everything forward of the pulley turns, so you can tell just by looking down on it from the top...you might just have to shine a torch on it when it's stationary to see some detail that you can focus on...if that makes sense.

i told him how to check to see if the clutch is engaging, what more do you want, strip the compressor out and stick 12v onto it.

i think my method is easier.

if the clutch is working and still no a/c 80% chance of not enough gas, the other cause could be the radiator is dead or else a sensor.

REDLAD123 · 21-07-2012 5:44pm

carbon nanotube wrote: »

firefly08 wrote: »

While that is all true (you can find out how to test a the clutch and relay on youtube in more detail) I still think you should keep looking until you can see if the compressor is turning or not...I am sure there must be a way you can see it. Knowing this will simplify life because if the compressor won't engage, then you can start tinkering with relays etc. but if it is engaging, and your cabin blower is working, and you're still not getting cold air, then you know it's something you can't fix yourself.

Here is a video that shows what you're looking for http://www.youtube.com/watch?v=vDIwq8JrAfQ

I realize you don't have that much clearance in the Audi to see it from that angle, but if you look closely you'll see that everything forward of the pulley turns, so you can tell just by looking down on it from the top...you might just have to shine a torch on it when it's stationary to see some detail that you can focus on...if that makes sense.

i told him how to check to see if the clutch is engaging, what more do you want, strip the compressor out and stick 12v onto it.

i think my method is easier.

if the clutch is working and still no a/c 80% chance of not enough gas, the other cause could be the radiator is dead or else a sensor.

Sorry guys I've been really busy in work so I didn't get near my laptop to reply. I have the car booked into my local garage Ryans Ballywilliam. They are going to check everything and degas the system if needed. Very eager to get the cold air blowing soon as its getting warm at last!!! :P

carbon nanotube · 21-07-2012 8:34pm

why not use my diy method

save you some money, your call.

i still think its the clutch but keep us posted.

REDLAD123 · 23-07-2012 10:44pm

carbon nanotube wrote: »

why not use my diy method

save you some money, your call.

i still think its the clutch but keep us posted.

It turns out that the whole front of the pulley had fallen off. The machanics just screwed it back on and put on a new pulley, regassed the system and voila !!! €125 all in..

Thanks for all your help guys.

Audi a4 Air Con not cold....

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