Yesterday it was freaking HOT and for the first time in a year, my AC failed to come on. The compressor clutch wouldn't engage.

I bought a can of refrigerant and a gauge, and went outside today to check the pressure, and it freaking came right on.

My pressure was right on the line between "filled" and "alert" - about 45 psi. Nowhere near the "warning" area of 60+ psi.

Could the hot weather have caused the refrigerant to expand and create too much pressure for the compressor to come on?

I let out about 3 psi today just in case that was the problem. I'm not sure what PSIs will trip the low and high pressure switches. Any ideas?

 

The fill cans and gauges cannot be trusted. The pressures to be concerned about are when the compressor is running. I would check the cycling switch on the receiver/dryer.

 

That was the pressure with it running. I was going to force it on with my laptop, but it came on by itself. I had to replace the cycling switch wiring about a year ago, but I'll check it again. I honestly didn't even think of that yesterday. I should have jiggled it to see if it would come on. Thanks for the reply.

 

Have you had your battery disconnected for any extended periods of time? If so, you might have to reprogram the a/c. I had to do it when I put the cam in. My a/c would intermittently work; sometimes it would run and sometimes it would flash the light and turn off.

 

I had an issue with the connector, it would work sometimes and not other times. I used some electrical cleaner on it and its been fine ever since.

 

my silverado has some cooling issues, sometimes it blows cold and really hot days it blows cool, im lost myself.

 

How exactly do you reprogram the AC? I just swapped PCMs and now my AC doesn't work.

 

Huh?

 

Is the connector union?

 

My ac isn't cycling from hot to cold, the evaporator is getting cold and the air is flowing thru the evaporator, but it is still blowing hot air??? Is there a way to manually cycle the blend doors without taking the whole dash apart?