No voltage to a/c compressor
Thread Starter
Pro
Joined: Feb 2007
Posts: 740
Likes: 2
From: San Antonio TX
Sorry it took a while, back from vacation. Yes I do have refrigerant , I bypass power to one side of pressure switch and it kicks on with 55 psig pressure at idle . Low pressure switch shows continuity, i just don't show any voltage going to switch.
Thread Starter
Pro
Joined: Feb 2007
Posts: 740
Likes: 2
From: San Antonio TX
Team Owner
Joined: Jan 2003
Posts: 20,305
Likes: 241
From: Summerland B.C. Canada
As RWDsmoke has mentioned, there is no power going to the pressure switches, they complete a ground circuit that goes back to ECM.
I can't 100% confirm this on your 91, as my info is from my C68 in my 86.
Maybe my info will shed some light, though.
http://members.shaw.ca/dankai/HVAC%20Electrical.pdf
I can't 100% confirm this on your 91, as my info is from my C68 in my 86.
Maybe my info will shed some light, though.
http://members.shaw.ca/dankai/HVAC%20Electrical.pdf
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Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Sounds like no gas - or too much gas - to me, though it would help to know the outside air temp. Contacts close at 50 psi, but static pressure should be in the '80's - assuming it's 70 or better - and once the clutch engages, the low side should be 28 to 38. If you've got 55 at idle with the clutch engaged, check the high side. If there's 55 static, check your low again as my guess is that it's dropping well below 25 psi which opens the contacts. If they're opening and closing rapidly - which they do when there's not enough gas - the ECM shuts down the compressor relay and your Panel will have a trouble code. Your '91 also uses a pressure sensor for fan control and as a high pressure cutout. If you have a scanner, you can see what it's showing or hookup a manifold gage set. Anyway, either condition - low or too much gas - shuts it down and it's going to stay shutdown until you fix it and clear the Code which you can do by disconnecting and then reconnecting the battery. You might just try that first and see what happens.
Race Director
Joined: Dec 2006
Posts: 10,383
Likes: 4
Look at this post. http://forums.corvetteforum.com/1570426699-post29.html
See if the ECC will tell you what's wrong.
See if the ECC will tell you what's wrong.
