Looking for Photo's or A/C wiring harness from an 85 K20 Truck

[Mark97213]

I'm having a tough time finding photo's of an Air Conditioning wiring harness on a 85 K20 truck. My 85 Silverado came with Factory Air, but the previous owner stripped all the engine bay Firewall to A/C wiring out. I have no idea why someone would do this. One would think it's not a factory A/C with wiring harness missing for A/C but it is indeed an AC truck. Does anyone have the time to photo their 85 Trucks A/C wiring harness in the engine bay?

 

[1987 GMC Jimmy]

So the stuff pre-firewall is still there, and you just have to wire up a prosthetic harness so to speak? I’d be more than happy to take pictures of mine, but I’m fuel injected so no idle control solenoid. If no one volunteers, bump the thread, and I’ll post up some pics.

 

[Mark97213]

Yes, the pre firewall stuff is there, the vents, the ac controller, just nothing coming out of the firewall for the to the evaporator nor to the compressor that once was there. It's odd. The housing on the evaporator also has no wired heatsink type controller that goes down into the evaporator housing as I saw in a few older chevy trucks I saw which makes me wonder if GM got rid of those in 85, but I have no idea because there's nothing there anyway.

 

[1987 GMC Jimmy]

You mean the resistor? That’s in the same spot across this truck line. That, the high speed relay which is mounted right close to there on the evaporator housing, the low pressure connector on the accumulator, and the wiring going to the compressor and dashpot are all the major junctions of the A/C wiring under the hood. I’ll take some pics tomorrow, plus it’s a TBI so there’s not a bunch of emissions junk in the way, and someone can fill in the one wire blank for what goes to the dashpot to bump up the idle when the clutch kicks on.

 

[Mark97213]

Yes, that's I think, a resistor. It has four, 4 inch prongs with springs at the bottom of them that drops down into the evap housing. That's the normal thing I've seen that goes into the housing but mine, has no hole to drop one down in it. But it's got no wiring for anything else either, nothing going to the accumulator like a relay or HP switch, nothing. And nothing going to what would be the compressor. Thank you for the pics, it will be SO appreciated. I just don't know where to start.

 

[Preston]

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Hope this helps

 

[SquareRoot]

I recently yanked my factory ac off my 85 K20. If you're interested, I'd be willing to sell you everything on the engine side of the firewall. Here's the only pics I have of it before it was replaced with Vintage Air.

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[chengny]

These images might help:

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Note that there are only 5 wires associated with the AC system that transit the firewall.

Three go to the blower resistor assembly and one each to the blower relay & pressure control switch (the other side of the control switch runs over to the compressor clutch).

In the engine compartment things get a bit more involved. Your best bet might be to go to the junkyard and surgically remove a combined electrical/vacuum tubing harness. To pull one takes only about an hour - even if you've never done it before. The vacuum supply tube and electrical harness share a common rubber grommet.

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First disconnect all the harness leads (the 5 noted above) and the vacuum tube from the carburetor/manifold. Then - using a screwdriver and some WD-40 - pop the common grommet back into the cab. With the grommet out of the hole in the FW, all the factory wires/connectors can also be withdrawn into the cab.

Then, when the complete harness is safely on the cab floor, pull the two connectors off the control panel (also the brown power supply from the fuse block). All that remains is to strip the electrical tape where necessary and remove the harness from it's hangers under the dash.

Oh and get all the engine side stuff too - that's only like 3 wires - everything else will have come into the cab with the harness.

 

[Mark97213]

WOW, thank you, thank you, THANK YOU. I really appreciate all you posted. This should help a GREAT deal.

 

[Mark97213]

Would that include the lines?

 

[chengny]

Would that include the lines?

What lines?

 

[Mark97213]

Pressure and return lines

 

[chengny]

Pressure and return lines

Oh yeah for sure - get whatever tubing you can. Especially the all aluminum liquid line from the condenser to the evap inlet. That is becoming really hard to find. It's no.16 in the dwg above - GM part 15568998.

The compressor suction and discharge lines/hoses are still readily available - and its probably a good idea to use new ones anyway.

 

[Mark97213]

Yes you're right, the main lines are still avail but like you said #16 would have to be custom made. What do you want for everything, aside from the main lines

 

[chengny]

Yes you're right, the main lines are still avail but like you said #16 would have to be custom made. What do you want for everything, aside from the main lines

Huh, what do you mean? I'm not selling anything.