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I have an aftermarket one (compressor) that's a single wire system and is grounded through the chassis. I'm considering replacing it with a factory AC compressor because that let's me use the factory size serpentine belt and idler pulley.
I'm not sure how many wires goto the factory compressor, and if only power is required, power and a ground wire to chassis, or if it also MUST have wires to the PCM, or if those can be capped/not used (dead terminals).
I have that and couldn't see a pin-out to actuate the compressor/clutch. I'm curious if the factory compressor can run with just the power wire, or if it needs a ground as well. Could always buy one and bench test it 😄
According to the schematic it gets power from the ac clutch relay through contact A, and a ground through contact B. I could run a separate ground wire from contact B to chassis and it should engage the clutch/compressor when I give the HVAC command.
Can anyone confirm if the factory compressor harness is a 2 wire system? I've been searching in the service manual for its pin-out but haven't found it yet.
[edit] so far all I can see is a 2 wire weatherpack connector one gets power from the clutch control relay through contact A, and Ground is through contact B and lands at G102 in the engine bay.
Last edited by 1994-LT1-Eric; Jul 27, 2021 at 09:24 PM.
The schematic I linked shows a 2-pin connector with 12 volts (dark green wire) on pin “A”, and ground (black wire) on pin “B”. Yes, you need the diode shown on the schematic, linking the two wires. The diode is “directional” and must be installed in the correct orientation.
The factory service manual will show you the location of ground “G102”.
Had a thought…… my A/C was deleted 20 years ago. But with all the other stuff that was deleted (ICM, MAF, AIR, cruise, etc.) the harnesses were left intact, just taped and hidden out of the way. Wednesday, weather permitting, I will see if the compressor harness is still there, and if it can be removed from the car relatively intact. If I can, it’s yours.
Had a thought…… my A/C was deleted 20 years ago. But with all the other stuff that was deleted (ICM, MAF, AIR, cruise, etc.) the harnesses were left intact, just taped and hidden out of the way. Wednesday, weather permitting, I will see if the compressor harness is still there, and if it can be removed from the car relatively intact. If I can, it’s yours.
That's awesome, I appreciate it!
I got serious about this AC not working for over 20 years and after fixing the electrical problems, discovered that one of my high side components is failing. When loading the correct amount of freon, the low side pressure will not go high enough, and high side pressure is too high. So if it's 100°F out the coolest I could get it without having high side pressure too high was 76°F at the vents.
So I'm pretty sure since they're over 25yrs old, the condenser and drier is clogged or not functioning correctly even though the cooling fan is blowing across it just fine. I cleaned it but it wasn't visibly dirty. Could also be thermal expansion valve, or compressor not working optimally.
Soooo, I'm gonna replace all of them (compressor, idler pulley, condenser, drier+low pressure switch, thermal expansion valve), I'll use a flush kit on the lines and evaporator. Pull a vacuum/ leak check, and recharge if all is good.
It currently doesn't leak, but can't get pressures right most likely due to old components. Driers are usually only good for 10 years anyway.
I had to fix and test what I have before going crazy with it lol 😄
I'll be happy to have a factory compressor/idler pulley/serpentine belt though (mine is all custom and not ideal), even if I have to rewire the power harness with a ground. I believe G102 is where the braided strap is fastened to the driver side of the engine bay. I should be able to use any sheet metal area of the chassis for ground, like up on the shock tower area where I have other grounds. I'll check it to the frame with a DMM to be sure.
No worries. Even if you don't have it, looks to be a simple 2 pin weatherpack style connector. I have plenty of wire, open barrel terminal crimpers, pins/sockets, soldering iron for the diode - so I can build a little 2 wire harness with power/ground, and use some split loom/zipties/clamps to route it.
Also in no hurry at all, I'm still researching the GM/OEM compressor (quite a bit more expensive than a standard parts house replacement), condenser, and drier. I have "unique" plumping of my drier because it's mounted in the front with the condenser and not back of the passenger engine bay like factory.
The ground strap grounds to the driver side frame rail (G109) and the other end attaches to the stud on the driver side head (G102) for the ICM/coil bracket.
Found the connector, hidden under/behind the alternator. Pealed back the sheathing, looking for the epoxied diode that is supposed to be “approx 16mm (0.63”) up from the A/C compressor clutch connector”. Nothing there.
I looked at Shoebox's clickable harness connector and I don't see anything that looks like it an inch or so from the connector. There may be something on the wire at the end of his sheathing, but it could just be the tape they wrapped to hold the end of the sheathing closed.
This is where they show the placement for some reason. It's no problem to window splice a 1A diode (directionally correct) with solder, so no worries I can build this. I'm just glad that the AC clutch/compressor are confirmed to be a 2 wire system. I can make this work by going back to a factory compressor.
You're the man! Thanks for looking at your setup for me.
