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Old 09-11-2002, 02:22 PM
Registered User
Join Date: Jul 2002
Location: Stony Brook, NY
Posts: 160
Question on electric connection to the compressor itself

Hopefully I can help you guys help me. I took a quick look at the compressor during lunch today. Briefly, my problem is absolutely no a/c. The blower works fine.

Well, it seems that the compressor is NOT kicking on. I though it was but it is not. I also thought this was the first time the a/c was used in the 2 weeks I've owned it. But my wife just informed me that she's used it twice and it worked fine.

I started thinking if I could have done anything to create this problem. I came up with one maybe. This past weekend I sprayed some degreaser on the front timing chain cover area from both the pass and driver side, let it soak and then hit it well with a pointed hose spray.

Is there any electrical connection on the compressor itself that my spraying or degreasing around the compressor could have dislodged?

Any other suggestions on what could make the compressor suddenly not kick in at all?


Ron B.
Ron Brooks
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Old 09-11-2002, 02:52 PM
I told you so!
Join Date: Jun 2002
Location: Motor City, MI
Posts: 2,804
Just a thought...... do you get 12v coming out of the wire to the compressor clutch? (Just trying to "bracket" your problem)
95 E320 Cabriolet, 140K
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Old 09-11-2002, 03:28 PM
Registered User
Join Date: Jul 2002
Location: Stony Brook, NY
Posts: 160
I'll test that tonight to see whether I do. I'm hoping maybe there is a clip or something I knocked loose. At least it's getting cooler here in NY and I will have many months to find and fix the problem before needing the a/c again. I'm just worried about a rainy night when the defrosters won't be working well without the compressor to remove the moisture.
Ron Brooks
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Old 09-11-2002, 03:56 PM
Keith Lucy
Posts: n/a
Testing AC components

This might help. Paragraph four goes through how to check the electrical connection to the AC compressor. P.S. Don't forget to check the fuse !!!

I had a problem with my AC and I found an answer on a different site. I'll post the info here in case anyone else needs it.

The AUX Fans are the two fans mounted in front of the radiator. They are triggered on when your engine temp exceeds 115C, OR the AC is turned on, AND has built up pressure. If you are low on freon, the system will not build enough pressure to turn on the AUX fans. This can be a big problem, as I will explain later.

To test the AUX fans, turn the key to the "ON" position (engine does not need to be running), and short the two contacts on the top of the AC drier. The AC drier is located behind the driver side headlight on the 560SEL, and possibly others. When you short the two wires together, you should hear the fans turn on.

To test the AC compressor clutch, turn the engine on, and turn off the AC. The forward portion of the AC compressor should NOT be spinning. If you short the two contacts on the SIDE of the AC drier, the AC clutch should engage and the forward portion should be spinning.

As I mentioned above, running the AC while low on freon causes high engine temperatures due to a slight domino effect.

First, it's hot outside, or else you wouldn't be using the AC.

Next, running the compressor without enough freon is harder to do, causing more work for the engine (I know because last night, while adding freon, the engine smoothed right out)

Next, because you are low on freon, the system will not build significant charge to trigger the AUX fans.

So now you have an engine, that is doing more work, on a hot day, and does not have aux fans running..... that will lead to a HOT engine (>110C).
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