Idle control when AC is ON

[kasmankk]

Hi, i need a little help. My e30 has an e36 m42 swap by previous owner.  My problem is the idle speed drops when AC is ON. As if the ICV is not responding.

I did some checking , all 3 signals to DME were not connected.
#48: compressor relay output
#85: pressure switch input
#86: anti stall input

My car is not using stock acond system. I am using an aftermarket electronic thermostat to control the compressor.

Anyway, i have figured out dme pin#48 and pin#85.  When pin#85 is grounded, pin#48 activated. And the ICV did respond.
But pin#86 does nothing if it is connected to 12V or GND or OPEN.

Any idea, on how what kind of input signal pin#86 is looking for?

Looking forward to hearing from you. Thank you.

[DesktopDave]

No idea. I'm curious too; that's a pretty common swap that'd be great info for the E30 owners on here. My A/C hasn't worked since before I owned the car, might also help with any R134 compressor upgrades.

[mad3]

not sure if im too late but i just discovered this after e36 m42 transplant into my e30

remove the AC button on the dash, check with a bulb tester to see which wires has +12V signal when turned on, splice this wire to the DME pin #48, or just splice the same way at the wire behind pin #48. This will tell the DME that the AC is switched ON.

Next ground pin #85 to any nearest metal you can find, that this might increase your idle a small bit but still less thank 1k rpm.

the idle rev hunt goes away and will not bog/stall each time you stop at traffic lights with the AC on.