Troubleshooting AC, 1998 GTP - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 10-10-2005, 05:31 PM   #1
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Default Troubleshooting AC, 1998 GTP

Well all of a sudden, sitting in the bank drive thru the AC went out. I checked all of the fuses, relays, and even replaced a small fuse looking thing called "AC diode." The compressor kicks on when it should, and the system is properly charged with no leaks. I have probably 3.5 hours in troubleshooting, and can't find the problem. The car has the dual zone electric climate control. Could it be a bad unit? The screen and buttons operate like they always have.
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Old 10-10-2005, 11:04 PM   #2
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Default Re: Troubleshooting AC, 1998 GTP

Quote:
Originally Posted by chasesmith
Well all of a sudden, sitting in the bank drive thru the AC went out. I checked all of the fuses, relays, and even replaced a small fuse looking thing called "AC diode." The compressor kicks on when it should, and the system is properly charged with no leaks. I have probably 3.5 hours in troubleshooting, and can't find the problem. The car has the dual zone electric climate control. Could it be a bad unit? The screen and buttons operate like they always have.
So the compressor is turning okay. Have you felt the tubes leading in and out of the evaporator to see if they are cold?

Is the blower motor working inside at all? Is the air coming out the defroster to the windsheild? Is that air cold? If so, that'* the default setting when you lose your vacuum feed. The programmer doesn't control the various valves that send the air where you've set the buttons to send it.

If you have air cold coming out the defrosters, check for vacuum at the vacuum tank under the right front, under the battery. it'* a plastic tank. you can pull the tube off by squeezing on two sides. Run car. If you have vacuum there and the tank seems to hold after the motor is off a few seconds. Then take out the glovebox and check for vacuum at the black line coming inside the car from the tank at the front. The black line has a light purple (okay is it violet?) tube connected into it. Pull hard, they'll come apart. Do you have vacuum there?
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Old 10-12-2005, 10:49 AM   #3
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The evap lines are nice and cold, the air comes out where I tell it to, not just the defrost, and the air is not cold. I don't know if the blower motor is working, because I don't know what the blower motor is. I am almost positive it is not a vaccuum problem, my Bonneville has that problem. Cold air blows out the defrost, but not the center vents (on the Bonneville). The GTP however, blows out hot air.
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Old 10-12-2005, 11:29 AM   #4
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Could this be a problem with the Temp Mix Door / actuator?

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Old 10-12-2005, 11:33 AM   #5
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Could this be a problem with the Temp Mix Door / actuator?
I believe this is the case.
If the compressor is working, air is blowing and everything seems great except getting hot air..it would need to be air temp mix.
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Old 10-12-2005, 11:34 AM   #6
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Quote:
Originally Posted by jr's3800
Could this be a problem with the Temp Mix Door / actuator?
Is that part of the control box under the dash? I am not very familiar with a/c systems, so you might have to break it down to like 2nd grade level.
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Old 10-12-2005, 11:46 AM   #7
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Quote:
Originally Posted by chasesmith
Quote:
Originally Posted by jr's3800
Could this be a problem with the Temp Mix Door / actuator?
Is that part of the control box under the dash? I am not very familiar with a/c systems, so you might have to break it down to like 2nd grade level.
The control box (programmer) controls the vacuum actuators that change doors inside the airbox under dash. These doors control where the flow goes...and if hot or cold is selectred. The bonus for you is because of the dual climate, you probably have two doors..one for each side.
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Old 10-12-2005, 11:55 AM   #8
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Sounds like a junk yard trip is in my near future. Thanks for the help guys.
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Old 10-12-2005, 12:12 PM   #9
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In the case of the bonnies ..you can see the air mix actuator from the glovebox. Wish I knew where you could see it if at all on the GP. That would help you greatly.
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Old 10-13-2005, 12:57 PM   #10
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Quote:
Originally Posted by chasesmith
I am almost positive it is not a vaccuum problem, my Bonneville has that problem. Cold air blows out the defrost, but not the center vents (on the Bonneville). The GTP however, blows out hot air.
You do know the easy fix?

http://www.imcool.com/articles/airco...acuum_line.htm

1/8 inch gas hose about 5 inches to bypass black connector for all 5 lines. Do not touch anything inside the programmer. Just cut the feed vacuum lines at the black connector and reconnect them. Make list of in colors vs outside colors before you cut off connector.
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