Originally Posted by bstill
check the low pressure service port, the pressure @ ~ 25 psi, then the clutch kicks in and the pressure increases to ~65-70 psi; this just loops - clutch kicks in pressure drops to ~25 psi kicks out raises back up to ~65-70 psi etc. Any suggestions for the shade tree mechanic?
Yea it's all BS, the clutch kicks on at roughly 15 PSI on chrysler. I did my own A/C etc... Anyways if you fully evac a system and charge it with the exact amount required the low side pressure should be at around 35-40 PSI if the pressure is around 50 then you may need a new expansion valve, thermostatic valves have refrigerant in a bulb as the temp of the bulb increases then the liquid refrigerant turns to gas thus increasing pressure thus opening the valve more allowing more refrigerant to flow thus colder air and lower low side pressure, I happen to have high side pressure around 65 PSI with full 3.75 Lb 134a, I need a new expansion valve but because I spent 60 bucks in refrigerant I'm not fixing anything until the refrigerant is done. Anyways I would look into checking the pressure if it's to high then you again should replace the expansion valve only if you replace the expansion valve be sure to replace the accumulator and any O-rings and the valve cores because the seals will leak if you use the old o-rings the valve cores leak as they age and the accumulator probably has collected much moisture, after all this evacuate the system on both high and low sides with a vacuum pump sustain 28 in Hg for 45 minutes to an hour then close valves and charge with refrigerant on the low side only, don't allow liquid refrigerant on the low side. When adding refrigerant do it with the car on and the AC on max, when the refrigerant can is opened the pressure from the can will triger the pressure switch to turn on the clutch will cycle on off on off a few times until you have enough pressure to prevent compressor burn out. any questions need any help just ask me I am more then happy to assist you.