I am charging my a/c system and have a question. When I set the a/c to max a/c the compressor clutch is locked and the compressor is spinning but when I put it to normal a/c the clutch does not lock up. Is this normal.
A/C Compressor Clutch Question
- Thread starter bordin34
- Start date
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Make-
Model-
Year-
Engine-
Factory system or add on?
The subscription for my crystal ball just ran out.
Model-
Year-
Engine-
Factory system or add on?
The subscription for my crystal ball just ran out.
slantsixdan
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'74 was the first year the A-bodies got an EPR valve and the compressor is powered full time when the mode selector is in "MAX", "A/C", or "DEF" positions (assuming the low- and/or high-pressure cutoffs are closed, if equipped). If your compressor clutch isn't getting power with the selector in "A/C", you have probably got a faulty selector.
tasvalowna
Well-Known Member
or a faulty thermostat
slantsixdan
=..=
Probably not a faulty thermostat (by which I assume you mean the evaporator anti-frost switch, which is the only thermostatic control in the system). Consider the symptom: the compressor engages when the selector is in Max A/C mode, but not when it is in A/C mode. The difference between those modes is the position of the fresh/recirc air inlet door. Electrically, those modes are the same. If the clutch circuit is being energised in Max A/C but not in A/C, that tends points to the selector. If the situation were opposite (clutch engaged in A/C but not in Max A/C) then the calibration of the anti-frost switch might reasonably be suspected to have drifted.
tasvalowna
Well-Known Member
my thinking was if the clutch stays in on max then the thermostat is by passed to allow the compressor to run full time . If when the aircon is taken off max then the thermostat is in operation and as the clutch wont pull in at all then the thermostst could be open circuit.
sorry Dan if im on the wrong track as i was unaware that all the max switch does in this system is change the flap from recirculate to fresh air
ben
sorry Dan if im on the wrong track as i was unaware that all the max switch does in this system is change the flap from recirculate to fresh air
ben
OwdKasd
Well-Known Member
Time to break out the Multi-Meter. My vote is it's a bad switch. The Clutch should cycle whether on Max or Fresh Air setting. I really can't see how an A/c T-stat could cause these symptoms.
slantsixdan
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Some Volvos and other cars with POE A/C systems were set up that way in the 1970s, but in the Mopar systems the difference is recirc/fresh air inlet and in some installations the status of the heater water valve, open/closed.
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