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No supply voltage to A/C relay

271 Views 11 Replies 5 Participants Last post by  MechBob, 
S
The compressor clutch on my 2001 Safari won't engage, so no A/C. It works when jumpered at the relay. All the A/C parameters are OK: low and high pressure switches are closed, voltage to PMC drops to ground when A/C is switched on. All fuses are OK. According to the wiring diagram, terminal D6, supplying voltage to relay, is supposed to have voltage when the engine is running. Mine has no voltage at any time. Turn signals and backup lights are fed from the same pink wire coming from the ignition switch and they work fine.

Has anyone encountered this problem? Any help would be appreciated.
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G
Have you checked the pressure readings with a gauge set?
There might be enough 134R left for the compressor to turn on for testing but not enough gas for it to run properly.
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AstroWill
SonomaDoug said:
Turn signals and backup lights are fed from the same pink wire coming from the ignition switch and they work fine.
Click to expand...
Yes, but they have their own fuses as well, did you visually check the IGN-E fuse or check it electrically?


I know it's in your post, but it's extremely helpful if your Year/Make/Model/Engine/AWD/Conversion/Mods/etc are listed in your signature and/or under your avatar so we know what we are working with both now and in the future. https://www.astrosafari.com/account/signature

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S
Ign-E fuse is fine both visually and via continuity check. 134R pressure is fine and both pressure switches are closed. I have checked everything I can think of, which is why I posted here. Van engine is not modified from stock.
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AstroWill
If you are getting voltage at IGN-E and the fuse is fine, then the problem exists between there and the connector for the relay.
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MechBob
2
Your A/C compressor is controlled by the PCM, No have 2001 diagram, but here is a 99 and 03--
Font Slope Rectangle Schematic Parallel

Rectangle Font Slope Schematic Parallel
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AstroWill said:
If you are getting voltage at IGN-E and the fuse is fine, then the problem exists between there and the connector for the relay.
Click to expand...
Yeah, I think that's my problem.
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S
MechBob said:
Your A/C compressor is controlled by the PCM, No have 2001 diagram, but here is a 99 and 03--
View attachment 290295
View attachment 290296
Click to expand...
My PCM is doing its job of sending the relay connection to ground when the A/C switch is turned on. As I stated, I have tested for that.
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MechBob
Well, pull the relay, see if the terminal is in place, sometimes they come loose, and get pushed down when relay is installed. Otherwise you will have to split open the fuse/relay box.
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ehbrown1
Make certain that the relay is A) good and B) installed the right way. Have found them in upside down already.
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S
On a day when the temp was 74 I had 77 lbs. of pressure in my a/c system. Turns out I was misreading my meter and I do have voltage to my a/c relay, but I don't have a clean ground from the PCM. Both pressure switches are closed. My relay only goes in one way and I swapped it with my fuel pump relay (which is the same) so I know it's good. I have an appointment with a Chevy dealer on June 1. They can deal with my PCM issue. I appreciate the help and suggestions.
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MechBob
Good luck. BTY if you have a SES light on, some codes may disable the A/C
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