I am adding the AC this week to my 86 2.5 and I see where the ECM gets a signal in two places. It looks like the ECM offers ground to these wires. Can I just ground these or do I need to add the wires in the two connectors for the ECM? I am thinking that the ECM might raise the idle speed a tad bit also. Has anyone else been here and know the scoop?
If I need to add the wires, does anybody have spare two wire connectors I can add into the harnesses?
Thanks
Joe Crawford

Pin 21 is an input to the ecm telling it the ac is on. It comes thru the hi and low pressure switches from the ac/heat console control.
Pin 7 is an output from the ecm to the compressor relay to turn the compressor on and off as needed. IE for hi/low pressure and hi engine loads.

Pin 12 is the ground for the ac part of the ecm and is probably already there.

Just FYI, don't know about the 86 prom for a 4. The 85 v6 prom does not increase the idle speed but a 4 may do so..

I have a compressor wireing map here, 12V comes out of the AC control head connection "G". It goes to the low pressure switch, to the high pressure switch, then it splits. One of the two goes to Ecm # 21. The second goes to the compressor control relay wire "A", then it comes out at"C" and goes to ECM # 7. It looks like the ECM is offering the ground to the relay if the conditions are met in the switches. I have the V5 compressor and the wiring is a little bit different , as there is no cycleing switch on the dryer /accumelater.

I'm thinking that I could skip the split and just ground "C" on the AC compressor relay. The two pressure switches still determine if the clutch comes on or not by offering 12V to close the relay, and send power through "E' to "B" on the way to the clutch.