AC compressor wiring question

[jsnppp]

This has been surprisingly challenging to find the answer. Been searching across all boards.

I am connecting my AC compressor on my 1991 318iS. I am at a loss where the clutch wire connects. I had the whole front end off for a few months and so cannot remember. When I cleaned the compressor I soldered a new wire in and so it can't help me find where it would fit.

Looking at schematics, I see the clutch wire goes to the red/black wire. The only one that I have is part of this 3 wire plug. However, this plug is currently (and possibly incorrectly) connected to a different set of wires. Huh!?







Question: Where does the single wire from the clutch connect to the harness?

Thanks in advance!

Jason

[monty23psk]

I have same car. Should be the same connector with only wire, in same terminal to match up against the single wire terminal coming from compressor.

[jsnppp]

Thank you Monty. It does appear that the compressor 3-pin plug should only have 1 wire, which then connects to the 3-pin plug in the car harness. I was missing the 3-pin plug that was connected to the compressor.

My next question is then what is the purpose of the other 3 pin plug (the last photo above)? I believe it's a red, black, brown wire.

~Jason

[monty23psk]

No idea. I see you have the radiator temp switch. I would have to look to see what other 3-prong connecter I have in that area. I will try in the next day to look and report.

[jsnppp]

I *think* it is my AC fan plug! Haven't tore into it but I bet I didn't connect it when I put it all together.. would make sense b/c it is thicker gauge wire, not signal...

[jsnppp]

Yes, I found my fan plug disconnected. The interesting thing is that it's on the drivers side, next to the ABS pump. So, that means I installed the fan 90 degrees off because I don't think the fan harness will reach as it is now...

Mystery solved! I'm almost ready to charge the system.

[monty23psk]

Yes, I found my fan plug disconnected. The interesting thing is that it's on the drivers side, next to the ABS pump. So, that means I installed the fan 90 degrees off because I don't think the fan harness will reach as it is now...

Mystery solved! I'm almost ready to charge the system.

Yes, I was going to say this could be it, but I disregarded it because it should be on drivers side. Looks like you solved the mystery.

[jsnppp]

Last night I rotated the fan assembly 120 deg and it all lined up. Was a bit of a challenge without taking the nose off but it worked. All wiring is in place and I pulled vacuum for about 45 min. I'll do another hour later today and hopefully charge it up.

Oh, have to put the glovebox back in, the last step after replacing expansion valve..

R134 conversion - will see what happens!

[jsnppp]

Of course, my low speed resistor is cooked! I did the various tests and it seems that it all is working other than that.

I've ordered a new magna resistor and dual temp switch... should be here next week.

[MikkoR]

I'm struggling with the same thing. I'm retrofitting the AC to my '84 323i, components are from different sources with no information about their background. I'm still missing the pressure switch(es), dryer and the wiring loom between heater matrix and pressure switch. The wiring loom I'll build by myself, not a big deal. But. My compressor plug has three wires going to the compressor, one black/red and two black wires. I believe that the black/red is for the clutch, but which are the remaining two wires? I've been studying the wiring diagrams and haven't found any help.

Edit: I have M20 engine, but I think it doesn't matter