A/C and idle speed

I have a 85 190e. The A/C comes on when ever it wants to. It doesn't run continously but will come on without a call for A/C. The push button controls don't seem to do anything as I have yet to turn on the A/C. Do I possibly have a bad control unit? Also after about 1/2 hour of driving, when I come to a stop, the car seems to idle below what it should and the oil gage will bounce a bit. I am worried that it will stall. When I put it in park it goes right to a smooth idle and the oil pressure stay even. Any thoughts would be greatly appreciated.

Thanks

[Benzmac]

You may have more than one problem. You need to have the idle circuit checked. The overvoltage relay is the first thing that comes to mind.

If the A/C goes into limp, it will act weird. There is a feedback potentiometer that sends voltage to the control unit. If the voltage is wrong, the control is nutty. Check for a vacuum leak under the air cleaner and under the battery.

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM