AC Clutch doesn’t disengage

[vallesfj]

Recently had my ac charged on my 92’ c1500. Runs nice and cold as it should but the clutch doesn’t cycle. When ac is turned on the clutch engages and stays engaged. Any ideas ?

 

[Awest623]

It isn't supposed to cycle while running, sounds like your AC is working as advertised.

 

[sneakingfart]

It isn't supposed to cycle while running, sounds like your AC is working as advertised.

Not exactly. I can cycle, from my admittedly very limited understanding, it has to do with refrigerant pressure, which is related to the ambient temps. Basically, if it's not that warm outside and there isn't a large heat load on the system, the low side pressure drops below the cutoff of the low pressure switch, and the compressor kicks off. As the refrigerant warms up, pressure rises, and compressor kicks on. Likewise, if the high side pressures are too high, the high pressure switch will shut the compressor off. If I'm wrong about these concepts, I hope someone here will correct me.

Long story short, he may have a problem or he may not. Without knowing those details it's hard to say. He would need to put a set of gauges on it and check pressures. If his ambient temps are in the 90s and his compressor is always running, it's probably normal. If he is in the 60s, it's probably not normal. Could be just the low pressure cutoff switch. But you would need to check pressures to be sure.

 

[movietvet]

An easy switch replacement is the low pressure switch at the accumulator. No need to open system and is relatively cheap. If don't have gauges, start there.

 

[1998_K1500_Sub]

Recently had my ac charged on my 92’ c1500. Runs nice and cold as it should but the clutch doesn’t cycle. When ac is turned on the clutch engages and stays engaged. Any ideas ?

Can you provide more details?

At idle it may not cycle, particularly if your c1500 is a Suburban and/or the AC system's under load (it's warm outside / humidity is high).

At higher engine rpm / higher compressor rpm, it should cycle, under the right conditions.

The best way to debug this would be to put a pressure gauge on the low side and confirm that the low-side pressure switch is opening and closing at the proper pressures.

Optionally, you can just swap the low-pressure switch with another and see what happens. @movietvet suggested this option.

FWIW, at idle my 1998 Suburban's compressor runs continuously in almost any reasonably warm weather.

 

[L31MaxExpress]

Over about 80-85F it will typically run continously at idle especially if the blower is running at 1/2 speed or more. If it is running continuously at highway speeds, it will very likely freeze the evaporator core up and airflow will be reduced or even blocked from the vents. I have had cycling switches fail myself on several GM vehicles.

 

[sneakingfart]

An easy switch replacement is the low pressure switch at the accumulator. No need to open system and is relatively cheap. If don't have gauges, start there.

True. Cheap and very easy to do. I replaced mine when I rebuilt the leaking components of the system in my truck. Literally, unplug the wire, remove, replace, profit. Should take less then 5 mins. Cost is about $20.