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A/C compressor never shuts off
Posted: Mon Feb 19, 2024 3:27 pm
by AtlantaDan
Previous owner installed all new A/C components, but something isn't right because the compressor (York) never shuts off or cycles. If it's plugged in via the low pressure switch - it's running. Even with the system off. Any ideas where I should start troubleshooting?
Re: A/C compressor never shuts off
Posted: Mon Feb 19, 2024 4:16 pm
by Srdayflyer
if the pressure sw. is disconnected the compressor should not run,period, were the a/c components replaced the same a factory ? , i would also check the on off/temp control sw. for proper operation , the switch may be broken internally and be on internally again with the L.P. disconnected it should not run, there should be only 2 wires going to the compressor, and the only thing those operate is the compressor clutch to energize the magnets to engage the fan belts, ground and power from the freon low pressure switch, the switch protects the compressor from running when no freon is in the system
Re: A/C compressor never shuts off
Posted: Mon Feb 19, 2024 4:40 pm
by will e
Are you familiar with circuit and the use of a multimeter?
Re: A/C compressor never shuts off
Posted: Tue Feb 20, 2024 3:52 am
by AtlantaDan
@srdayflyer - if the pressure switch is disconnected the compressor stops running. That's the only way I have found to turn it off. I'll start poking around under the dash. I was wondering if the thermistor has anything to do with this problem - does an 89 AC system have one of those?
@Will - Yes, I am familiar with a DVM and circuits.
Thanks!
Re: A/C compressor never shuts off
Posted: Wed Feb 21, 2024 7:32 am
by Srdayflyer
Re: A/C compressor never shuts off
Posted: Wed Feb 21, 2024 11:50 am
by Stuka
There should also be an override so that if you have the AC turned off in the cab, it disconnects the clutch so that the compressor isn't engaged.
Re: A/C compressor never shuts off
Posted: Wed Feb 21, 2024 1:59 pm
by will e
AtlantaDan wrote: ↑Tue Feb 20, 2024 3:52 am
@srdayflyer - if the pressure switch is disconnected the compressor stops running. That's the only way I have found to turn it off. I'll start poking around under the dash. I was wondering if the thermistor has anything to do with this problem - does an 89 AC system have one of those?
@Will - Yes, I am familiar with a DVM and circuits.
Thanks!
Great! That will help.
So if the pressure switch is connected the compressor always turns on. Regardless of any other control settings?
If that's the case trace the wire from the switch to its next location or power source.
Curious. Does the compressor clutch engage even with the ignition turned off?
Re: A/C compressor never shuts off
Posted: Sun Mar 03, 2024 8:20 pm
by seventynine
Something is not right here. You say it’s a York compressor? They were using Sanden compressors starting in ‘89. York compressors don’t have low pressure switches. They are oiled via their own internal crankcase oil supply. The will turn on with or without Freon in them….which is why they make great onboard air compressors
It must be a Sanden right?