I have a 2002 Ford Explorer with AC that is not cooling. The AC clutch engages, then cycles off and repeats the process over and over. With a gauge on the low side port, the pressure rises to around 65 psi when the compressor is off, then drops in seconds down to nearly 10 psi. Does this indicate low AC pressure? I have always seen the pressure pretty much stay static at a certain pressure....haven't ever seen it fluctuate like that from low to high as the compressor kicks in and out.


Thanks!

 

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Refrigeration system works the same as the pickup.

 

With the system off and the high side and low side equalized, it should have about 100-120 psi static. It pulling the low side down to 10 psi quickly when running seems like it is low on refrigerant.
With the windows open and the AC set on max and recirculate, the low side should hold steady around 40-45 psi if its around 80 degrees out with the compressor running constantly. Once you turn the blower down to the lower speeds, the compressor should cycle normally on the low pressure switch.