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A/C Problems

2002 Silverado A/C Clutch Not Engaging

A/C Problems

Postby PJLiberty01 [OP] » Aug 13 2020, 11:12pm

So a wile back my ac stoped working. The clutch wont engage. I spent $400 on a new compressor, pressure sensors and a charge. Still no luck. I tested the voltage at the low pressure sensor and it was 12v, then at the high pressure .08v from the PCM. Not sure what the voltage is supposed to be at the high pressure switch but im sure that .08 is far too low. I've checked all of the wiring, fuses and relay and they are all good. I tested the ac button and it works and the light comes on. The clutch does engage when I jump pin 30 and 87 on the relay but wont work otherwise. I think its a PCM problem because ac request volts are so low but im not positive. I've been working at this for weeks and don't know what else to try. If anyone knows something please let me know, thanks!
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Re: A/C Problems

Postby EaOutlaw1969 » Aug 14 2020, 9:49am

I am not sure if this will help because it is for a 2003 ( possible slight differences ) I found this link on line for you the guy seems pretty knowledgeable and has access to data I would want when trying to diagnose a problem like this. From what I read the .08 Volt to 1.0 Volt at static pressure is normal.
Here is the link the information below came from https://www.2carpros.com/questions/2003 ... noperative
Second link mentioned from the first source https://www.2carpros.com/articles/how-to-check-wiring

Testing compressor clutch/wiring:
Key on engine off, Jump the A/C clutch relay from pin 30 to pin 87, Compressor clutch should "click". If no click, check for power at the green wire at the compressor. Check the black wire for ground.

Testing low pressure switch:
With the truck running, A/C turned on. Check the dark blue wire at the low pressure switch for five volts with the switch Disconnected. Check for ground on the black wire. With the switch plugged in both wires should show ground. If the blue wire still shows five volts. Your low on Freon or the low pressure switch is bad.

Testing high pressure switch
1. With key on, disconnect the A/C pressure sensor and check for five volts on the gray wire. Check for ground on the black wire.

2. If missing either circuit, check a few inches back from the connector and see if voltage or ground is present there.

3. If the above checks are okay, then plug the sensor back in and probe the red/black wire of the sensor and see what voltage is coming from the sensor. With static A/C pressure voltage should be 0.8-1.0 volts.
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Re: A/C Problems

Postby Walkers » Aug 14 2020, 2:57pm

I would start by.swapping the relays. If your compressor does not run how much gas were you able to put in?
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