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Discussion Starter · #1 ·
Stumped by A/C wiring. Installing 97 NAS 90 factory AC unit in my 94 NAS 90 and I'm not sure how to rewire the 97 harness, or if it can even be done. Looking at the 97 diagram I have no idea how to bypass the GEMS engine components.

Should I proceed with trying make the 97 harness work, or should I ditch all of it and make a new harness?

Here are the resources I've acquired so far. 97 wiring diagram. 94 wiring diagram for reference. Vintage Air wiring diagram, might be the best option. The two plugs pictured are for the 97 4.0 GEMS main harness. So 8 wires that need a home. The rest works, I think.





 

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Oh, this is racking my brain. I put a 97 AC retrofit kit in my 300tdi almost 20 years ago so I’ve almost completely forgotten how I did it. I do recall that I failed to incorporate the high and low engine temp switches, so my Tdi ray switch wasn’t completely doing its thing, I would have had to shut the AC off if the motor was overheating but that circumstance never occurred. The system eventually failed because the custom AC lines were badly constructed. I eventually disassembled the system and sold the parts.
 

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Discussion Starter · #3 ·


yeah I’m nearing the point of selling and buying a new kit.

The other thing I can figure out…the v-belts don’t line up. The width between engine belts, is greater than the width between new compressor belts. based on some 94 pictures I found with original setup, it looks like it came that way from the factory. The aft belt lines up. The forward belt, not so much. Did they only run one belt originally?
 

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So one thing to keep in mind is that 97 trucks were 4.0l GEMs motors and included an AC compressor whether or not AC was equipped. Therefore the kits had no compressor. if this is a takeout from a 97 then why is the compressor not a polygroove serpentine pulley? Kinda confused about what equipment is here.
 

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Discussion Starter · #6 ·
I bought compressor, hose kit and condenser from vintage air. Wiring is the only missing link. The rest I can make work.
 

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Only the back belt slot goes to the AC compressor. Ignore the front V belt channel as that is only used for the water pump to crank. My 94 NAS is set up this way
 
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