Engine AC compressor stays running?

91GTstroked

15 Year Member
Jun 14, 2007
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Okay guys,

I have some other things to try and fix. Here's the deal. I have a mark iv electric fan with a painless relay.

Once the fan turns on at 180* my AC compressor starts running. It does this with the ac controls turned off!

I noticed this because my ac lines get frost on them without actually turning on the AC.

Just bought the car last May, so trying to figure things out.

Thanks.
 
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Also, can I just disconnect the wiring harness to the ac compressor if I don't want it to run?

The car has the painless 30103 relay.

 
I'm going to jump in here and say look at the wiring that turns on the fan when you turn on the ac, something is likely hooked up wrong.
Someone will jump in here now, I usually give bad advice and they follow me around and correct it. :doh:
 
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I usually give bad advice and they follow me around and correct it. :doh:
CT! :rlaugh:

Okay guys,

I have some other things to try and fix. Here's the deal. I have a mark iv electric fan with a painless relay.

Once the fan turns on at 180* my AC compressor starts running. It does this with the ac controls turned off!

I noticed this because my ac lines get frost on them without actually turning on the AC.

Just bought the car last May, so trying to figure things out.

Thanks.
Is the defroster turned on when this is happening?
 
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Does the compressor turn off again when the fan does. If so, you likely have the signal from the AC to your fan controller hooked up wrong.

Not sure how you have it hooked up so hard to diagnose.
 
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Does the compressor turn off again when the fan does. If so, you likely have the signal from the AC to your fan controller hooked up wrong.

Not sure how you have it hooked up so hard to diagnose.

I believe it does. It's set at one fan speed. Turns on at 180 and stays running. I can manually shut fan off.

I can't figure out why they have it wired like that. I rarely ever use AC.
 
So I disconnected the ac compressor harness. Fan turns on and stays running like it should.

Then I look further down on the wiring. It appears someone connected a red wire to it. Not sure why they want the compressor running full time?

Either way, should I disconnect it? I might leave the whole thing unhooked for now. I never use the AC. Maybe delete it at some point.
 

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So I disconnected the ac compressor harness. Fan turns on and stays running like it should.

Then I look further down on the wiring. It appears someone connected a red wire to it. Not sure why they want the compressor running full time?

Either way, should I disconnect it? I might leave the whole thing unhooked for now. I never use the AC. Maybe delete it at some point.
They probably cross-connected it like that to bypass the safety switch due to either the switch or another component being bad. That was a bad idea on their part, because if the pressure in the system gets too high, you can have an explosion (though usually no fire unless the PAG oil hits the headers), and if it drops too low, the compressor can catastrophically lock up due to no oil circulation.

On a side note, @General karthief should be happy now.
 
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They probably cross-connected it like that to bypass the safety switch due to either the switch or another component being bad. That was a bad idea on their part, because if the pressure in the system gets too high, you can have an explosion (though usually no fire unless the PAG oil hits the headers), and if it drops too low, the compressor can catastrophically lock up due to no oil circulation.

On a side note, @General karthief should be happy now.

Makes sense. I just disconnected the red wire, hooked the harness back up to the compressor. AC blows cold, and the compressor cycles on and off, which I believe it's suppose to when I have the AC turned on. Stays off if the control is off.

Maybe I'll delete that red wire.
 

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Some help for you to see how it is supposed to be wired...
Click on the drawing to enlarge it for easier viewing...

5.0 wiring diagram for Fuel Injectors, Sensors, and Actuators
fuel-alt-links-ign-ac.gif
 
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