2003 Saab 9-3 SS, 25k miles, 2.0T engine
Maybe you can advise me what to do. Last week, after not having used the A/C for a while, only ambient temperature air came out when I turned it on. When turning on and off the A/C, I hear no click or engine load as if the compressor clutch is engaging. Previously it was working perfectly. I checked the compressor fuse and relay. OK. Pulled fuses on all ECMs and ACC for 30 minutes. Still doesn't work. For about 30 seconds I shorted the compressor relay contacts with the engine running and this time you could hear the compressor kick in. But no cold air. Can losing refrigerant cause the electronics not to allow the compressor to come on (except if forced on by shorting the relay contact)? Is there a common flaw in this make/model? How can I troubleshoot further before taking it in? Regards.

Somewhere around 65-70% of all A/C problems are low refrigerant charge. The very first step is see what the static pressure is in the system and note the ambient temp in F. At moderate temps 134a will be about the same in PSI as the temp in F.

A/C is not supposed to engage compressor at low temps or low charge - it can't tell the difference but knows the pressure. Compressing low temp refrigerant would quickly cause hydraulic lock so we don't want that - there's enough screaming in the world!

Don't be jumping things electrically either. A/C is also linked thru puters for adjusting idle speed and electric fans, temp controls - let's not go there.

This more than likely has a leak so try to prove it's low and let's go looking for where it is - your witnessing it clicking on at all, already rules out a lot,

T
Tom Greenleaf - MetroWest Boston - USA
http://www.acsource.com/

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http://www.autoacsystems.com/tomgreenleaf/