AC Pressure diagnosis

[gapost]

My 03 Sierra is not cooling. It was not getting below 60 degrees while driving and higher while idling.

 

I figured it was a little low on freon so I put about 12 oz. in. I know the system takes about 32. It got a little cooler, but not much.

 

My pressures: idle at about 92 degrees - 60-62 low and about 320 high. I know that seems a little high. While driving, my pressures at 92 degrees are about 45 low and about 210 high. Temperature from the center outlet is barely 60 degrees while driving. My compressor is running basically all the time and there is water coming out the drain.

 

I'm half tempted to evacuate the system and start fresh with 32 oz, but wanted to get some opinions as it seems the pressure is a little high on the low side while driving. If I evacuated the whole system, I would probably change the expansion valve. Could that be making my low side a little high and not getting the cooling down into the 40's??

[Jsdirt]

Sounds like a bad fan clutch, or you have air in the system - got to vac it down for a while depending on how much moisture and/or air is in the system. I usually let it run for a half hour then shut the pump off for 10 minutes to make sure it's not leaking. Check for debris between the condenser & radiator also, and blow out both.

[8.1HD/ALLISON]

+1 on above. At 90 degrees the low side should be around 30-40 psi max I believe at idle. Spray your condensor out with a garden hose. Check cab filter if you have one also.