Str|der

Hello fellow Audi owners,
My 2005 S4 stopped producing cold air. It's now even cool. Was on my way to Mexico and a/c stopped working. Stopped in some small town and finally found a place with some r 134a which I tried to fill but maybe about 1/2 the can went in...months later I finally get some manifold guages and check the hi and low pressures. I figured the "parts replacer" I bought the car from did didn't do a good job putting the ac back together. So I was surprised when I saw that when the car was off the hi and low matched at about 70 psi.

I had the constant econ button light took apart front to get to high pressure sensor tested that by applying pressure and checked for any voltage. Why do some places/catalogs refer to it as a high pressure sensor/thrust sensor?

Get that back in charge system with a can of r134a and am now able to get the econ light to go out. The drivers side fan kicks on but I don't notice any change in speeds. Can't get the passenger side to even turn.

The manifold guages show no to very minute change, which could be my hopeful eyes. At most 1 psi when the ac is turned on. When the ac is turned on I can feel a slight vibration in the engine and here a small change but no real change in guage readings and no cold air.

I tried locating the compressor from the top and when it was on jacks from the bottom and I just can't figure out where it is located. Well I know where it's located but I can't seem to find it. How do I find it? Even tried at night with a black light but no luck there either. Someone talked about a plate on the cover but I can't find that either.

So my question, finally, is are the pressure readings good or do I need to charge it some more to get the other fan to kick on? How do I locate the compressor? How do I narrow it down a bad compressor? If the drivers side fan is busted will that stop the ac from engaging? What other trouble shooting steps should I take?

Thanks for any assistance.

Str|der

I put her back on jacks and i just can't figure out how to see the compressor. Anyone ever do this before?

Str|der

When I bought my s4 the washer fluid would leak if you filled it about 3/4. While trying to work on the ac figured I'd look at that also. Have the top part lose but there is a hose underneath the washer fluid storage. Have the felt like part above the wheel off and can see the windshield washer fluid motor and another storage. Can I pull that hose between them without damaging anything.
Thanks again.

s4master1

it appears to me your compressor has failed due to overheating as one radiator fan was not working to lower heat/pressure.
the compressor is located under the exhaust manifold on the driver's side, is driven by a shaft that connects to the rear of the engine.

Str|der

Thank you very much. Will return the manifold gauges since replacing the compressor is not something I would even think of doing.