Hello, I was wondering anyone can help me out with a very tricky A/C on my 92 100s. The system has a full charge but the compressor will not stay on. It will turn on and off every 2-3 seconds. I managed to find the system relay and force the system on and it will blow very cold air but I'm not sure on what part I need. I know there is a speed sensor on the compressor and the Audi tech said if the speed sensor is bad the compressor will not stay on long enough to cool.... thus will not keep the relay engaged. Is there such a part? Or any advise on repair? I have spent close to $600 and the Audi dealer is not even sure on what the cause is. All they said is the compressor is good and the problem is elsewhere. (that figures) May I also add the pressure safety was tested and found to working correctly... so I'm so lost Help![&o]

Thanks for any help

Chris

 

The pre '91 models used a Harrison CCOT (GM) system and they were supposed to cycle. I don't remember if Audi used the same system on the later models. Under normal conditions the AC compressor is supposed to cycle on and off otherwise it will ice up and freeze.

The head unit should have a diagnostic mode and there should be a way to check the parameters but I am not familiar with the 92 100. If the head unit doesn't report any error codes then you might have a flap or a servo that is not functioning properly or is broken.

I have not heard of any thing like a speed sensor on the compressor but logically it would make sense. How many wires do you have going to the compressor?