AC electrical problem
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Joined: Nov 2012
Posts: 53
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From: Oshkosh Wisconsin
AC electrical problem
Recently my AC dash panel goes dead when I first start my car. After about two minutes it comes on and works fine. It puts out great AC once it kicks in!
Any ideas what to look at?
Any ideas what to look at?
Safety Car
Joined: Mar 2017
Posts: 3,762
Likes: 937
From: Orlando Florida
Dual control system? The panel shows no lights, and there is no fan or anything else going on when 'dead', yes? Not just the typical too dim to read cutting in and out? I'd be suspicious of a bad ground. There has been a pretty in depth thread on the system recently with much good input from C5_Diag and UselessC5. Considerable troubleshooting and several wiring diagrams:
https://www.corvetteforum.com/forums...ermittent.html
https://www.corvetteforum.com/forums...ermittent.html
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,435
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From: Cape Coral, Florida
First off what year is the car ??...your profile shows a 1979 ??...can you edit your profile so we know what we're dealing with...using the DIC see if you have any HVAC or any codes stored...if you see a U code relating to the HVAC (HVAC No Comm) it may be a power or ground issue....do you have any other components inop like your rear window defogger or inside rear view mirror ??
Last edited by C5 Diag; Jun 8, 2023 at 05:50 PM.
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
YEP,, Read and post ALL your DTCs. You have to figure out if the unit is getting the PROPER POWER to the head unit. Just like C5 Diag stated, Our C5 have issues that can cause problems to be seen in numerous other modules or parts of the car caused by ONE THING..
Seeing how you know that you are having a problem with your HVAC, you can get a Multimeter and find the FUSE for the HVAC Module. It will be in the Passengers Footwell Fuse box. When you experience the issue with the HVAC being dead, measure the HVAC Fuse voltage.
On top of each fuse are two small test points. Turn the ignition switch to ON and measure BOTH test ports to a known GOOD Chassis ground.
Both test points should read FULL BATTERY VOLTAGE to ground. If you see something LESS that full battery voltage, post up the voltage that you see and we will point you in the correct direction.
Bill
Seeing how you know that you are having a problem with your HVAC, you can get a Multimeter and find the FUSE for the HVAC Module. It will be in the Passengers Footwell Fuse box. When you experience the issue with the HVAC being dead, measure the HVAC Fuse voltage.
On top of each fuse are two small test points. Turn the ignition switch to ON and measure BOTH test ports to a known GOOD Chassis ground.
Both test points should read FULL BATTERY VOLTAGE to ground. If you see something LESS that full battery voltage, post up the voltage that you see and we will point you in the correct direction.
Bill
