JDM Mighty Boy A/C Wiring and mystery Black/Red Tracer wire?

MightyBoy tech questions and answers.
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classwinners
Posts: 1
Joined: Mon Jan 08, 2018 1:30 pm

I have a very stock original 1987 JDM Mighty Boy F5A with factory A/C. The A/C compressor is not kicking in -- it has r12 gas pressure, so I've been investigating wiring. I found a broken white wire behind the glove box, then a white and black/red tracer both taped off near the edge of the glove box. My wiring diagram shows white runs interior lights and brake switch, but I see no black/red wire on the diagram. It also lists a blue/red tracer for "AC" connection. Also weird is that in my fuse box under the dash, the location marked A/C is actually not connected with any wires -- and hence no fuse. The HVAC unit's A/C light turns on green when pushed, so some current is getting to the right location. Since this is a JDM late production car, I'd guess things are different than earlier cars.

So any ideas here? What is that black/red tracer wire? and The black wire from the compressor in the engine bay goes into the loom, but I don't see where it connects.
Cheers,
Sam in Washington USA
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Brayden
Posts: 9101
Joined: Sun Apr 11, 2004 3:09 am
Location: Canberra ACT
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Very few MBs in Aus have aircon, which probably explains the lack of response. The wiring diagram only suggests the black/red wire is for 'A/C connection' but is also wired to the heater coil and switch, so it's likely a +12v trigger for a fused relay to the A/C pump clutch. That would explain why the green A/C light is illuminating.

Wiring diagram: http://www.teammightyboy.com/workshop/3 ... ng-diagram
F8B EFI turbo - Three pots and a snail.
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