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roybelding, Master Tech/Trainer
Category: GMC
Satisfied Customers: 5718
Experience:  35 years of retail operations on all vehicles
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GM Sierra: Diy'er trying to troubleshoot AC on a 2006 gmc Sierra.

Customer Question

Diy'er trying to troubleshoot AC on a 2006 gmc Sierra. Replaced the belt and tensioner within the past few months and was working fine. Compressor doesn't seem to be engaging currently. Worked fine for a month or so. Ideas?
Submitted: 2 years ago.
Category: GMC
Expert:  K. Wiggins replied 2 years ago.
Hello, do you have a gauge set to see if it has enough refrigerant to allow it to trigger the low pressure switch?
Customer: replied 2 years ago.
When I replaced the tensioner and belt last month, I also purchased refrigerant and filled it using the gauge that was provided with the can. My understanding is the compressor must be engaged before I can check the refrigerant level. I do not know how to check the low pressure switch.
Expert:  roybelding replied 2 years ago.
good afternoon my name is ***** ***** I will assist
you need at least 20-50 on the low side for the compressor to engage. the pressure can be checked with the engine off. without that pressure, the switch will not close and the ac will not work.
I assume you have the gauge you got with your kit. that will be good enough to check for any pressure.
freon level cannot be verified by gauge readings. lets start with a check for pressure
Customer: replied 2 years ago.
The gauge shows 100 lb of pressure, and possible a mechanical problem.
Expert:  roybelding replied 2 years ago.
the static pressure should be close to outside temp what mechanical problem??? do you have a test light or voltmeter to check for voltage at the compressor clutch?? Roy
Customer: replied 2 years ago.
I have a volt meter, but don't know exactly where or what to check voltage on!
Customer: replied 2 years ago.
Replied with pic of gauge.
Expert:  roybelding replied 2 years ago.
ok, get the voltmeter and check the voltage at the plug on the compressor. unplug the wire at the compressor. use the red lead from the voltmeter to the plug and the black lead to the negative of the battery. set the voltmeter to dc volts and turn the key on, ac on and see if there is any voltage at either of the wires on the plug. Roy