2002 Avalanche Air Conditioning

I just purchased a 2002 1/2 Ton 4X4 Avalanche and love it! I have had an intermittent problem with the air conditioning however. It will work every now and then but not all the time. I tried to see if it was an electrical problem and when I pulled the switch off of the side of the accumulator and jumpered it, the A/C worked for a time. I have checked all the fuses, and have replaced the switch at the side of the accumulator, but it seems the A/C has a mind of its own and works when it wants to. Any ideas what may be causing this?

biceps1

Put on a set of guages and tell us the pressures.

Put on a set of guages and tell us the pressures.

I put a guage on the low pressure side and it is a 45 pounds. I used the gauge from the R-134 refridgerant. The pressure seems to be in the ideal range on the accumulator.

biceps1

The low side should be 35-40. Your system sounds low.

We need your low and high side readings at idle and at 2K rpm with compresser runnung.
MT

Bring this one back up for thoughts. I have a 2002 Avalanche I am working on as well. It is about 80 degrees here today. The pressures at idle are 275 high side, and 45 low. If you run it at 2000 rpm, the low does not go down much, but the high will go as high as 450 psi. What I noticed is that the compressor does not shut off. Even with the AC switch in the off position! If you turn the system controls to off it will shut off. Or if you shut off the fresh air and the recirc buttons, it will shut off. Is it possible the high pressure cut out is bad? If so where is it? Why would it be cold sometimes, and sometimes not? Any ideas are greatly appreciated!!

On your problem you need to start a new thread/post.
Saves on hijacking.
High presures can be cause by over charge or to much oil in system or not enough air blowing threw rad and ac condenser and overheated engine.
Try a good floor fan in front of rad and see if pressure drops back to normal.
And check the clutch fan for proper operation.
You should hear and feel a lot of air from fan when engine/rad tempt goes over 200.

If fan is working and a floor fan does not bring it down hit the condenser with a water hose.

ON HIGH PRESSURE AND AIR IS BLOWING THREW RAD GOOD.
Pump the R-134a And vacuum system for moisture AND PUT THE PROPER R-134A CHARGE IN IT.
The recheck pressure and post back.
MT