A/C compressor not turning on?

HD1200

MEMBER
2003 CHEVROLET SILVERADO
V8
4WD
AUTOMATIC
215,000 MILES

I’m trying to get my A/C working. The problem I’m having is the compressor is not coming on. I can jump 87 and 30 on A/C relay and compressor comes on. I've tested low pressure switch with the switch unplugged. I have ground on black wire and on blue wire I have 4.57 volts. I plug in connector on low pressure switch and have ground on black wire and no ground on blue wire and blue wire still has 4.57 volts.

I have evacuated and charged system. I have 24 oz. In the system I know it needs 2 more oz, but in my pass experience the compressor should have come on after 2 cans of Freon.

I’ve changed low pressure switch but still the same result.

I’ve checked the green, white wire from pin 43 and I have no ground there.

I’ve changed PCM over this and it’s still doing same thing.

It takes a couple of pushes to get the button on control panel to come on its manual control. Could a faulty control panel cause this?

What should I check next?

Thanks

4 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,513 POSTS

It sounds like you have a bad HVAC controller, but we should check for power at the system fuses, I have included a guide and the A/C system wiring diagrams below so you can see how the system works and which fuses to check. I would check the grounds as well.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Here is how to change out the HVAC controller in case you need it. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

Images (Click to make bigger)