Need some help with my A/C PLEASE

[AK49BWL]

You can check that with a test light or voltmeter. At the pressure switch that's not connected yet, connect your test lead to the light green wire and the other lead to ground. If it works, problem isn't the module. If not, it may still not be the module, but you can do that same test at the bottom pin on the gray connector of the module. If it works there but not at the pressure switch, then the problem is somewhere in between. If it doesn't even show voltage there, then yeah your module is shot.

The A/C Request wire goes from the control module to the firewall bulkhead connector behind the convenience center on the driver side, then out to the high pressure switch, then to the PCM. It does not control the relay, I repeat, the PCM controls the relay, not the A/C switch in the control head.

 

[Bigred81]

You can check that with a test light or voltmeter. At the pressure switch that's not connected yet, connect your test lead to the light green wire and the other lead to ground. If it works, problem isn't the module. If not, it may still not be the module, but you can do that same test at the bottom pin on the gray connector of the module. If it works there but not at the pressure switch, then the problem is somewhere in between. If it doesn't even show voltage there, then yeah your module is shot.

The A/C Request wire goes from the control module to the firewall bulkhead connector behind the convenience center on the driver side, then out to the high pressure switch, then to the PCM. It does not control the relay, I repeat, the PCM controls the relay, not the A/C switch in the control head.

 

[Bigred81]

Ok. New update. Went back to the mechanic to have Freon vacuumed out so I could put in new pressure switch. My system was drained. I found a bad o-ring in the back line after tracing all of the ac system with a UV light. Fixed the O-ring and put in two bottles of Freon. Had to jump the compressor for it to work. With ac jumped the front vents are cool and the back vents are very cold. I can live with that. I will try what you recommended to test my controls. Thank you very much for helping me. I’m obsessing over this. Even with new Freon I still have same issue with compressor not engaging. That is my only problem. I don’t want to just put a wire in there to jump it for it to work. Been a 100 degrees here and I get heat stroke easily. I’m a ginger in a desert state. I put in a new control center from the junk yard. It’s in good shape. Same symptoms but maybe it was bad too.

 

[HotWheelsBurban]

Ok. New update. Went back to the mechanic to have Freon vacuumed out so I could put in new pressure switch. My system was drained. I found a bad o-ring in the back line after tracing all of the ac system with a UV light. Fixed the O-ring and put in two bottles of Freon. Had to jump the compressor for it to work. With ac jumped the front vents are cool and the back vents are very cold. I can live with that. I will try what you recommended to test my controls. Thank you very much for helping me. I’m obsessing over this. Even with new Freon I still have same issue with compressor not engaging. That is my only problem. I don’t want to just put a wire in there to jump it for it to work. Been a 100 degrees here and I get heat stroke easily. I’m a ginger in a desert state. I put in a new control center from the junk yard. It’s in good shape. Same symptoms but maybe it was bad too.

Wouldn't be surprised if the control center is bad or starting to go. These trucks eat those switches. My other 99 Burb went through 3 in a year. 2 brand new Delco ones, after a "good " used one. At least the parts house warranty'd the first Delco. The second one was still working when the truck got wrecked. It and the stereo stack are going in this Burb when it's not quite as hot. Going to get a cheap pickup from my boss's family tomorrow, to DD so we can have cool air. He thinks it needs a can of freon but I can't fix the Burb for what he wants for the truck.
Glad you're starting to have some progress on your Burb though. I'm the only one in my family who doesn't immediately get sunburned outside so I feel your pain there!

 

[Bigred81]

Wouldn't be surprised if the control center is bad or starting to go. These trucks eat those switches. My other 99 Burb went through 3 in a year. 2 brand new Delco ones, after a "good " used one. At least the parts house warranty'd the first Delco. The second one was still working when the truck got wrecked. It and the stereo stack are going in this Burb when it's not quite as hot. Going to get a cheap pickup from my boss's family tomorrow, to DD so we can have cool air. He thinks it needs a can of freon but I can't fix the Burb for what he wants for the truck.
Glad you're starting to have some progress on your Burb though. I'm the only one in my family who doesn't immediately get sunburned outside so I feel your pain there!

Man I wished I could comprehend electrical systems to trouble shoot this. Just doesn’t click with me. I’ll probably just buy a new control center. Is it possible it’s my PCM?

UPDATE: I got my volt meter out. All switches had 13v. The head unit tested out good. Green cable had nothing then I pushed ac butting and it jumped up to 13. Started checking fuses for the hell of it. The first fuse I checked was the 10A IGN-E fuse. It was blown. I put a new on in and the AC works now. I think I replaced it a month or so ago. I hope it doesn’t continue to blow, but atleast I found the cause. Thank you again for all your help guys. I greatly appreciate it and I e learned a lot.

 

[HotWheelsBurban]

Man I wished I could comprehend electrical systems to trouble shoot this. Just doesn’t click with me. I’ll probably just buy a new control center. Is it possible it’s my PCM?

UPDATE: I got my volt meter out. All switches had 13v. The head unit tested out good. Green cable had nothing then I pushed ac butting and it jumped up to 13. Started checking fuses for the hell of it. The first fuse I checked was the 10A IGN-E fuse. It was blown. I put a new on in and the AC works now. I think I replaced it a month or so ago. I hope it doesn’t continue to blow, but atleast I found the cause. Thank you again for all your help guys. I greatly appreciate it and I e learned a lot.

Thanks for the update! Sometimes we are lucky and it's a little thing. My boss's mom's 99 Suburban wouldn't start last weekend and he called me, because he knows I know more about Chevy trucks than he does. Turned out to be the crank fuse; I told him to check that first. It's easier than checking the crankshaft position sensor or the starter.