Automotive Air Conditioning Information Forum

Hello,

I have Audi A6 from 2006. When I rev the engine past 2000 rpm the AC stops working. If I rev the engine again I hear a hissing sound and the AC starts working normally. I made a video with live data. As you can see from it, the gas pressure drops immediately after I rev the engine and the evaporator temperature rises rapidly. Any ideas what is causing the issue.

https://www.youtube.com/watch?time_cont ... mzufjhHgRM

zafirovp wrote:Hello,

I have Audi A6 from 2006. When I rev the engine past 2000 rpm the AC stops working. If I rev the engine again I hear a hissing sound and the AC starts working normally. I made a video with live data. As you can see from it, the gas pressure drops immediately after I rev the engine and the evaporator temperature rises rapidly. Any ideas what is causing the issue.

Nice computerized thingee, but I want to go back to basics. Is the compressor clutch actually engaged over 2000 rpm, take a look. And if not engaged, is that AC clutch getting 12 volts positive?

As far as I know this is clutchless ac compressor. The only thing that is engaging is the AC regulating valve n280.

This compressor has a clutch hub. Just hidden.

No RPM readings in the video, so it is hard to determine what is going on there.

The regulating valve never moves and a pressure sensor shows what may be the high side going all over the place.

Without actual system pressure from both the low & high side & an RPM reference it is all guesswork.

Since you have three different vent temperature sensors, I would wonder about a control system issue / sensor failure.

When you increase engine speed, the compressor capacity increases. the high side pressure should increase, the low side should drop - and the control valve should shift compressor capacity to manage things. You appear to have a swing of over 120 psi on the high side with no change in control valve setting.

Sounds like you may need a dealer level scanner.