HT4100 4.1, 4.5, 4.9 Discussion, Can anyone interpert this A/C gauge reading?? in Cadillac Engine Discussion; Long story short, the A/C blows cold then warm in six second cycles. This issue is being dealt with in ...
Long story short, the A/C blows cold then warm in six second cycles. This issue is being dealt with in another post, but I would like to know if anyone could interpert this gauge reading? I went to put two cans of 134a in the low side port and got a start reading of 45psi at about 90 degrees local temperature when the clutch turned on in the first cycle. When the clutch turns off (blows warm air) the pressure gauge climbs to 90psi, then creeps to 96psi and the clutch turns back on, drops to 50psi for a few seconds, creeps to 42psi and the clutch shuts off and the cycle repeats, WTF!!! It's going to an A/C shop this coming week, but I still would like to know what it's doing, any ideas?
Certainly the low pressure side is too high. There should be a maximum of about 60 psi on the low side with the engine shut off.
The cycling switch should kick in at these higher pressures and pull it down to abour 20 psi before it cuts out. I'm guessing that the high side gets so high that the high pressure switch is sutting off the compressor to protect the system.