I had my 82 300SD running the other day and tried testing the compressor by removing the leads on the low pressure switch and shorting them. I did not see/hear the compressor kick in. I'm not sure I had the A/C on though due to the fact that I've never run it. I assume I had to push in the button next to the defrost as well as the "high fan" button? I don't have any blown fuses.

If I were pressing the right buttons, could I have a bad relay?

anyone?

I believe your '82 SD has the automatic climate control. If it does, press in one of the buttons with the up and down arrows, not the EC button. Make sure your temperature dials are all set to the coldest setting. When you jump those wires you should see/hear the compressor clutch pull in. Make sure the pigtail connector on your compressor is properly attached.

Scott

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Scott
1982 Mercedes 240D, 4 speed, 275,000
1988 Porsche 944 Turbo S (70,000)
1987 Porsche 911 Coupe 109,000 (sold)
1998 Mercedes E300 TurboDiesel 147,000 (sold)
1985 Mercedes 300D 227,000 (totaled by inattentive driver with no insurance!)
1997 Mercedes E300 Diesel 236,000 (sold)
1995 Ducati 900SS (sold)
1987 VW Jetta GLI 157,000 (sold)
1986 Camaro 125,000 (sold - P.O.S.)
1977 Corvette L82 125,000 (sold)
1965 Pontiac GTO 15,000 restored (sold)

Yes, I have ACC. I pressed the button next to the defrost which is a solid up and down arrow. The temp was set to cool as well. I didn't check the pigtail though (not knowing about it). Is it easy to see from the top or is it accessible from the bottom?

You need to press the center button on the ACC.

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RRGrassi


70's SPM #5608 Fairmont A-4 MOW car

06 VW Jetta TDI 145K miles

82 300D 300K My Daily Driver-Warndreicke in the trunk. Trip ODO still working!

90 Dodge D250 5.9 Cummins/5 speed. 260,000

ah.....and that is why I posted....thanks.

The pig tail to the compressor is at 3 o'clock when looking at the front of the compressor, or 9 o'clock when looking from the back. Either way, it's easier to access it from under the car.

Just because a compressor clutch engages does not ensure the a/c compressor is working. I'm replacing a compressor again, due to clutch failure.

__________________
RRGrassi


70's SPM #5608 Fairmont A-4 MOW car

06 VW Jetta TDI 145K miles

82 300D 300K My Daily Driver-Warndreicke in the trunk. Trip ODO still working!

90 Dodge D250 5.9 Cummins/5 speed. 260,000

I just tested it again and I hear the clutch. The PO said the system was working so I'm going to go on the assumption its ok. I did find out that the system is empty. I am going to vacuum it, change the evaporator and expansion valve and add oil and freeze12 (with a bit of stop leak). I'll let you know how it goes.