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2003 Suburban intermittent compressor

418 Views 1 Reply 2 Participants Last post by  Markmx6
The Suburban compressor randomly works. No reason is apparent. When it works, it cools really well. I suspect the pressure switch, however sometimes when it stops working, it changes to inside air. Is there anything that might cause this effect?
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If you are low on refrigerant the compressor will cycle on and off. Basically the compressor will cycle on > High side pressure will increase and low side will decrease> the low side will decrease below the set point for the low pressure switch > the switch opens and the relay shuts down the clutch on the compressor > the high side pressure will decrease and the low side will increase as the system equalizes > the low side pressure will now exceed the setpoint for the low pressure switch > the switch closes the circuit and the relay engages the compressor again and the cycle repeats itself.

You can put a set of gauges on the system and verify this is your issue, or you can buy a cheap refill kit from (insert local auto part store here or walmart etc...) that should have a low pressure gauge and you can at least watch the low side.

You can also remove the connector to the low pressure switch (on the accumulator / receiver drier) and use a paperclip or small piece of wire and short the two pins on the wiring side (not the switch) This should allow the compressor to stay on. Do not leave it like this, you are just verifying that low charge is the issue. If the compressor stays engaged, you need to add refrigerant to the proper level otherwise you will burn up the compressor clutch because it wears each time it cycles on or off, or if you force the clutch on with low refrigerant you will burn up the compressor because the refrigerant circulates oil through the system and you can guess what happens with any moving component does without oil...

The inside air part is probably a programming thing to try and keep the passenger compartment a little cooler. Once you have the system charged properly that most likely will go away too.
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