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I've checked all the relays, fuses, and connections with the A/C system. The compressor still won't turn on. Is there anything else I can check or miss with before I know I have to replace it, could it possibly be a different problem than the A/C compressor. What is the procedure for it being replaced? I looked around and saw that have to have someone Vacum the system and recharge it. Is there anything else I have to do?
 

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If it is low on freon or oil it will not turn on. You have to have someone vacum it down to see if there is any leaks and if there isnt then they can recharge it.
 

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Disconnect the connector from pressure switch.

ACpressureswitchjumped.jpg


Jump both pins with a paper clip on the electrical connector
Have someone watching the A/C compressor while you start the truck and turn the A/C on. If the compressor cycles on, turn it off.
You now just narrowed it down to either low refrigerant or a bad pressure switch.
 

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bump. my compressor clutch wouldn't engage. i bridged the low pressure switch, and it kicked on. do i need to get some gauges on it to see if it's charged? what should it be at? is there any way i can check the low pressure switch? is it supposed to have a certain resistance or anything?
 

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so i went to HF and picked up a cheapo gauge. threw it on the low pressure side (closest to accumulator) and its reading just shy of 65 psi. according to the marking on the gauge thats the max safe pressure. so does that mean its the low pressure switch?

also, i put it on high with the windows down and the compressor kicked on. i saw in my haynes manual they said to do that to keep the compressor on while charging.

does the fact that the compressor came on point to something else? i know the switch units in the dash are notorious for going out.
 

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JUGS Racing
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No. Theres a schrader valve to prevent freon from escaping when you replace the switch. Just make sure you dont overtighten it.
 

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This is on a 2004 gmc p/u I have checked the fuse and relay all good. I have jumped high pressure switch .I have no power going to the high pressure switch wiring is good. What else is their to check besides the switch in the dash
 
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