'02 A6 AC stopped working

The AC in my car suddenly stopped working. I don't think the compressor is moving at all. There is no change in idle speed or sound from the engine
when I turn the AC/heater unit on and off. There is a fuse marked heater/AC or something like that but it's not broken and I guess if it was, the heater unit would not work at all. I think there is an electrically operated "clutch" that connects the compressor to the drive belt. Could this thing be on a separate fuse? How do I find this "clutch" and the wires that controls it? Anyone know how I can troubleshoot this?
Jone
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"Jone Tytlandsvik" <jone> wrote in message

If your AC has a display, you will be able to pull the fault codes from it by pressing a combination of buttons. Unfortunately, I don't know what these will be for your model but a search on the internet might help you.
Good luck
Ian
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It helped when mine went dead in Italy last month.
Ronald
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5potnoodle wrote:

I found these codes but they are for '90 model and may not be the same for my car. http://www.audifans.com/twiki/bin/view/Audi/HVACDiagnosticCodes
Jone
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Jone Tytlandsvik wrote: .

These codes seems to be the correct ones for my '96 A4 but not for my '02 A6.
Jone
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"Jone Tytlandsvik" <jone> wrote in message

First check that the AC compressor belt hasn't snapped - it'll be down the front of the engine.
Second engage the AC & then feel the AC lines - (usually aluminim looking things routed around the side of the engine bay) one should go cold pretty quickly & you should see condensation. If it does go cold then the AC is working & try changing your cabin pollen filter - that worked for me on an A4 a couple of months ago when we thought the AC had died.
If the line doesn't go cold then either the compressor/compressor clutch has packed in or you have a big leak & have lost all your AC fluid (in which case don't drive the thing too far). The fluid also acts as a lubricant & without it the compressor will sieze if it hasn't already.
rgds
Iain
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Iain, If the AC system lost pressure, the low pressure switch would cut the power to the magnetic clutch and the pulley would just freewheel - part of recharging a system when it is under vacuum is bridging the low pressure switch to get the compressor to run. Jone, Chances are, if you turn the system full cold and you don't hear the occasional click of the clutch engaging on the compressor, and with the engine off you can turn the compressor by hand (you can do it so long as the clutch isn't welded to the pulley) will indicate that the AC has probably lost enough pressure to activate the LP switch. If you can find the location of the switch - it's a wired pressure transducer teed into an AC line - and bypass it (for a short time to avoid burnout) to make the clutch engage and run the system, then the system has lost some pressure. Cheers! Steve Sears 1987 Audi 5kTQ 1980 Audi 5k 1962 and '64 Auto Union DKW Junior deLuxes (SPAM Blocker NOTE: Remove SHOES to reply)

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Steve Sears wrote:

Thanks, Ill give it a try tomorrow. I also noticed today that the electric radiator fan is running even though the car is cold. It should not do that should it? If some faulty sensor tells the computer the engine is hot, could it turn of the AC in an effort to keep the engine cold?
Jone
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On Sat, 09 Jul 2005 01:12:52 +0200, Jone Tytlandsvik <jone> wrote:

panel.. On our 97' model the fan ran although the LP switch had detected low pressure and disengaged the compressor (clutch open). So your problem most likely is a normal loss of refrigeration gas. Most workshops will fill up the system for less than 2' NKR.. The prosedure takes about an hour as it involves complete drainage, vacumtest and refill..
The vacumtest however will not always detect small leakages. So if you loose gas within a few weeks a check using tracing liquid and ultraviolet light will be necessary. Got this for free, as I filled twice in a month.. had to change one line due to pittings under a plastic shrink fit hose at a suspension point..
regards ottar t
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Steve Sears wrote:

On newer cars it's not a switch but some kind of pressure transducer. So you have to find out what resistance that will make the clutch engage. But my car is at the Audi garage now. Hope they can figure out what's wrong.
Jone
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