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Old 07-16-2014, 03:39 PM   #1
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Default Troubleshooting AC issue

1998 GMC Savanna 1500 120,000 miles and isn't cooling.

Symptoms are: With AC on and in max cold position temperature doesn't cool below 68 degrees with the outside temp at 68. Turned controller to max heat and temp raises to 98 degrees within seconds. (My 2002 Sierra will cool to 42 degrees within seconds). No condensation is dripping below the vehicle in the front or rear. (Has rear heat and air). Can not hear the compressor start or engage when I turn on the system after start up or when driving down the road. Shop says pressure readings are good and freon is charged to specs.

I am suspecting the compressor is bad, can it be something else????

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Old 07-16-2014, 04:29 PM   #2
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how could your reading be good and the compressor not engaging. read across the compressor with a meter, if you have power and its not engaging its something with that, if you dont, there is a pressure sensor that goes to the computer and the computer tells the compressor to engage. hard to tell if all that is good unless you have one of the expensive scanners that says whether or not its good.
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Old 07-16-2014, 10:48 PM   #3
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Verify your getting 12V at the compressor connector. If not, then either the PCM isn't commanding the A/C to turn on because of lack of sufficient signal from the A/C lines, or the PCM is not seeing the request for it.

You need to visually verify that the compressor is not running.
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Old 07-16-2014, 11:52 PM   #4
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Symptoms are: With AC on and in max cold position temperature doesn't cool below 68 degrees with the outside temp at 68. Turned controller to max heat and temp raises to 98 degrees within seconds.

Your temp should rise to 140-150F on max heat, if the vehicle is at normal operating temp.....

No condensation is dripping below the vehicle in the front or rear. (Has rear heat and air).

Condensation is more a product of humidity.....

Can not hear the compressor start or engage when I turn on the system after start up or when driving down the road.

Have someone turn the A/C on and off several times....does the compressor cycle on and off?

Shop says pressure readings are good and freon is charged to specs.

Was this just a static test, or were there readings with the compressor running? Was system recovered by weight and refilled by weight?

I am suspecting the compressor is bad, can it be something else????

Like Mike said, turn A/C on and see if the clutch engages......if it doesn't, disconnect and attach a test light to the harness connector of the clutch and turn the A/C on and see if the test light comes on.....

Does your accumulator have a pressure cycling switch on it? If yes, disconnect harness, jumper it together and then turn the A/C on and see if the compressor runs.....if compressor runs and the low side line is cold, and pressures are ok, then you need a new switch.....
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Old 07-28-2014, 09:52 AM   #5
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Thank you for your suggestions and help. My shop did all the items suggested and after test where done the compressor was replaced. I took the van on a 1200 mile journey and used the AC the entire time with no issues and worked as it should.
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Old 07-28-2014, 11:19 AM   #6
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Awesome news, glad you got the AC fixed, there is nothing like having a working AC in the summertime!
Thanks for updating us.
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