a/c diagnosis help

[JDEstill]

My a/c hasn't worked in a while. I kinda figured the compressor had frozen up since it's been 3 years (or more?) since I last used it. Last night I had DirectScan on the car and I noticed that when the slide is moved to an A/C position I don't see the A/C request flag come on. This was both with the engine running and also at key on/engine off.

Now I'm wondering if I've really got a mechanical problem, or if its an electrical issue.

So my main question is, what is it that alerts the ecm to an a/c request? Is it a pressure switch, is it the position of the slide lever, or what?

I've done some research through the archives, found some good stuff about the various switches and relays in the a/c system, but figured the answer to this question might help me narrow down my troubleshooting. It would be nice to find out that my problem is something simple! I was assuming I was going to have spend some major bucks to get the a/c functional again.

John

 

[salvageV6]

Pressure switch has to be closed to generate the A/C request, jump the switch out and it should appear on direct scan.

Probably no freon in the system however so if you run the car you can see if the compressor is free and clutch works but don't run it more than 10 seconds or so without a charge.

Vacuum the system and check to see if it holds before recharging would be your best bet whether converting or using R12.

 

[JDEstill]

Thanks salvage! Seems like most of the good posts I found on this topic had your name attached to them. Got a bunch of good stuff when I searched on "a/c" and "salvageV6". I appreciate it!

John