I am trying to finish up my a/c diagnostic. I get no voltage from pin 10 to pin 5 of the pins on the Klima relay. Therefore, I am not getting ground signal. How should I track this down? The A/C is fully charge and blows cold when I jump pin 5 and pin 7. I know the season is getting cooler, but I want to finish this project. This is on an 86 420sel.

Thanks,

John

John,
The pushbutton must send ground signal THRU the low pressure switch on the drier to pin 10 of the KLIMA relay.

Most common problem other than pushbutton is the evaporator temp sensor.

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I got voltage across the low pressure switch. The evaporator temp sensor is still a pain to get at. I did not get any voltage across the temp sensor at the drier when the car is running. But when I jump the compressor, the aux fan does come on. I am not sure that if the engine temp sensor is activating this or the drier temp sensor. I bypassed the temp sensor at the drier, still no AC.

How do I check the evaporator temp sensor exactly? Is there voltage when the PBU is engaged and no voltage when PBU is not? How many volts?

Thanks,

John