2000 Chevrolet Silverado 1500 No AC

Hi guys I’m looking at my grampa’s truck and the AC stopped working. It was a bit intermittent for a while but pretty dead now. This is the 5.3 Vortec V8 engine. I hooked my gauge to the rear access port where i was told to hook it up and the pressure is high. I also pressed the valve and refrigerant shot out so it seems that it’s not a low refrigerant problem. I’ve never dove into AC systems before but I was reading about various switches and relays to check but they didn’t cover very well what to check. I know the AC compressor is at the bottom of the bay and from what it looked like the clutch wasn’t spinning. Any help on where to check next would be appreciated. Thanks!

If the freon level is indeed good, and thats a big if, there is no reason the compressor shouldn’t be turning. If the freon is low it will shutdown to prevent damage. You could price replacement clutches to see if worth the gamble. From my knowledge the “center”
of the pulley will be turning when clutch is engaged, it sits still when its not (only the outer diameter of the pulley spins when not engaged). I always take my a/c issues to the pros.

This is good advice. Don’t make a simple problem serious and expensive. If you don’t know what you are doing you can hurt yourself.

I’ll read between the lines and guess that you connected a parts house can of R134 that has a gauge on it. If so the gauge is calibrated to read the pressure on the low side when everything is operating as designed. When properly filled with R134 with the AC turned off(or not working) that gauge should read about 90psi. When a proper set of gauges is connected both gauges would read about 90psi with the system not running but with the AC operating properly the low side would drop to about 30 and the high side to 225 to 325psi.

You are almost certain to be hooked to the low side and until that gauge gets up to about 30psi a switch won’t allow the clutch to operate. If there has been a problem with the pressure the control module may not allow the clutch to operate.

First what was the indicated pressure that seemed high to you?

And FWIW I agree with @Mustangman above. Things bursting when a DIYer unfamiliar with the operation and not properly equipped is a common result.


I don’t consider air conditioner work a do it yourself item .
I also wonder why someone would choose ( birdbrain ) as a screen name.

1 Like

The gauge value speaks for itself, idk why it’s maxed. it didn’t really change whether the AC was on or the car was off. In the other pic i used the rear port.

The fittings on that system require proper connection of the high and low side lines and that makes it somewhat certain that you are reading the pressure on the low port and it is also somewhat certain that the AC compressor was not operating regardless whether the engine and AC switch were on.

Just for the sake of possibly eliminating some confusion, yes, the rear fitting is for the low(operating) pressure and the fitting a foot to the front is the high pressure fitting. When operating properly the refrigerant leaves the compressor under high pressure, passes through the condenser at the front and rearward to the evaporator. the threaded connection between the high and low pressure gauge fittings is where the orifice tube is located. The orifice is a where high pressure is forced through a very tiny hole and as it passes through it becomes a vapor and the temperature drops significantly. When off the pressure equalizes in the system in a few minutes.

You must track down why the compressor clutch is not turning the compressor or if it is turning why it is not drawing down the pressure on the low side. Get an AC repair manual and the shop manual for that pickup and read up on how the system works mechanically and electrically then if you don’t give up post back.