CUTLASS AC compressor plug/main power plug help

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84dragcutlass

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Okay so im looking for help sorting out my cobbled together AC system on my 87 Cutlass. First ill start by saying when i bought the car all the AC had been removed and all the harness was removed so i dont have any of that for reference. I have installed a complete AC box with the harness that goes along with it to run the blower and had the connection for the relay and such. What i don't have is the plug for the AC compressor clutch itself or the main plug that connects to the main plug of the AC box harness (usually connect behind the distributor area if i remember correctly). My front harness is from a 1986 cutlass that i pulled to switch to the 4 front headlight version. My question is where does the plug for the AC compressor clutch originally come from, how can i add i back, and where does the main plug for the AC box wiring harness normally come from and how can i add that as well. Trying to sort all this the best i can because as we all know it seems like none of these 30+ year old parts seem to be complete.
 

ELCAM

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84dragcutlass

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Thanks that helps a bit, i think i might have figured out some of my issue. It seems on the computer controlled cars the main plug that powers the HVAC unit is tied in with the computer harness. So my 87 would have originally had that hence why i have no wiring left, the 86 harness (driver side main harness) would have also been computer controlled and it would have been the same situation as my cars original. So i went back and looked at the 86 parts car and found the main plug within the computer harness. Doesnt do me a whole lot of good since the wiring on that is so hacked up but it does explain a few things at least. Within that wiring write up i dont seem to see what actually engages the compressor clutch but i think i might be able to get it to work.
 

69hurstolds

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This MAY help you some. From the 87 CSM. 2nd pic shows VIN Y/9 on the left, VIN A on the right. Sorry for the crappy quality, but that's how I roll.

87 AC Compressor Control wiring A.JPG

87 AC Compressor Control wiring B.JPG
 

84dragcutlass

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So if im reading that correctly, after it goes through the pressure cycling switch i can pretty well bypass the ECM step and run the DK green wire to the AC compressor clutch from there it seems.
 

69hurstolds

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Yeh. You could ground that brown wire for the A/C relay the way I see it, bypassing the ECM control. Leave the cycling switch to come on/off by itself, and it should work just fine when you turn on or off the A/C. The 87 ECM controls the full throttle cutout on the V8 cars negating the need for the switch that's above the gas pedal under the dash from previous years. So you'd probably lose the cutout feature at full throttle with the A/C on. Other than that, I don't see much issue here. I've never done it, and not so electrically inclined, so not 100% sure of what would happen there.
 

84dragcutlass

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I didn't know about the cutout feature, learn something new everyday. Id have to keep that in mind for the future. I guess just have to cobble this thing together and cross my fingers that i can get the switch to control the off and on function enough that it would work. This is the part that sucks about piecing together an already cobbled setup that you didnt dismantle in the first place. Lucky i really like this car.
 

69hurstolds

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So if im reading that correctly, after it goes through the pressure cycling switch i can pretty well bypass the ECM step and run the DK green wire to the AC compressor clutch from there it seems.
I read that wrong. You said "dark green" which is the VIN A, or V6 side. Yeah, that would make a difference. I assumed you had a V8 car originally.

The ECM isn't needed to engage/disengage the clutch on a V6 according to the diagram. It just gets inputs whether the clutch is getting the signal to be "on". The pressure switch and controls are technically already hooked up to the compressor clutch.
 

84dragcutlass

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Aug 20, 2009
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North Vernon IN
I read that wrong. You said "dark green" which is the VIN A, or V6 side. Yeah, that would make a difference. I assumed you had a V8 car originally.

The ECM isn't needed to engage/disengage the clutch on a V6 according to the diagram. It just gets inputs whether the clutch is getting the signal to be "on". The pressure switch and controls are technically already hooked up to the compressor clutch.
I believe this car had a V6 from the factory, really hard to tell since all that was long gone when i got it. The only real indication that i have is the throttle cable was the V6 length rather than the longer V8 version. However that being said the AC unit that i installed is from another unknown car, the front wiring harness (headlights, horn, starter, etc.) is from another car (1986) So its all kind of a Frankenstein since all of the original components were gone when i got the car. The only thing i am really missing in the whole equation is the main plug that powers the AC unit itself and the compressor clutch wiring. So those diagrams will be a big help and knowing i can use that pressure switch (I'm assuming that's the one on the dryer)
 
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