Quote:
Originally Posted by 75sierraclassic
I just bought a 2003 Silverado LS with 160,000 miles. The A/C has been giving me fits. Sometimes the compressor will turn on sometimes it won't. The A/C button in the cab is sticky but the light on the button comes on every time I push the button to turn on and turns off when I turn it off. It seems to turn on when the truck is cool but if you shut the truck off and turn it back on when its hot (with the A/C button still on) the compressor won't kick on. I put some hoses on it and took pressure readings but I'm not sure what they should be. See below. Ambient temperature was in the low 90's. I ran it for about 10 minutes and the compressor never cycled.
Engine RPM: Idle 600
Low side PSIg: 62
High side PSIg: 320
Cooled Interior Air Temp F:66
Engine RPM: 1500
Low side PSIg: 290
High side PSIg: 45
Cooled Interior Air Temp F:56
Engine RPM: 2000
Low side PSIg: 45
High side PSIg: 280
Cooled Interior Air Temp F:58
I tried to jump the low side pressure switch when the compressor wouldn't turn on and it still didn't turn on. I havent tried to jump the high side switch.
Any thoughts on what it could be?
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Do you have a Manual A/C or Auto A/C control head?
Those pressures are high. 320 PSI of head pressure is hard on the compressor. Check clutch fan operation, Check for a clogged condenser, A/C system maybe over charged..Spec is 1.6 lbs of 134A, clogged orifice tube, To much refrigerant oil..Spec is 7.1 oz.