Who is the hvac tech in here? I am trying to get my ac relay to operate and provide power to the ac compressor. I have the pressure switches jumpered to ground. Ohmed all the wires out the relay will not click when I turn the ac on. Only when I jumper the signal wire to ground then it functions. I thought maybe an open ground but the all ohm out.
ac wiring 1997 c1500
- Thread starter zach1999
- Start date
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Ok I'm going to start fresh here maybe someone could give me a hand. The ac diagram shows a light green wire from the ac switch going to the low pressure cutout. The wire has 12v on it when the switch from the dash is engaged. Is that right does 12v really go into the low pressure cutout switch? I thought those were supposed to be signal wires to activate the relay and then send power to the compressor. Thanks again any help is appreciated.
I'm not sure about your 97 but, the pressure switches don't go to ground, I think they should be in series with each other or in a circuit by themselves back to the Convenience Center so it will then, turn on the compressor.
The light green wire should be going to the high pressure switch, which has to be closed for the AC demand signal to make it to the AC demand input on the PCM. Both the low pressure cutout (compressor mounted) and the clutch cycling switch (accumulator mounted) have to be closed and allowing the signal from the ECM to be pulled to ground for the dark green and white AC relay control wire to be grounded and engage the relay. If you can ground the cycling switch and the compressor cycles, then the high pressure cutout and low pressure cutout are good and you have either a faulty cycling switch, bad ground on the cycling switch circuit, or system pressure is too low for the switch to close. Diagrams I'm using for reference are attached.
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Bypassing all three switches won't do anything if there isn't a AC demand signal coming from the control switch. Do you have 12V at the AC demand pin on the ECM when the AC is turned on?
I haven't delved that far into it all I know is it ohms out from pcm pin to command pin on relay so no broken wires
Alot of head scratching, I have power at all fuses inside and out i have power at pink and orange wires at relay I have power at all switches, for whatever reason my scanner wont tell me if there is a ac request in pcm. have went about 6 years without ac because of this issue.
The results are in I now have a functioning compressor and can now address further issues with my system. For anyone having similar issues I recommend looking at your wiring from the switch on the back of the compressor.
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