degreased engine, now A/C doesn't work! - PeachParts Mercedes-Benz Forum

WANT '71 280SEL · #1 08-25-2006, 07:37 PM

(300SDL)Yesterday afternoon I took my car to work and with the engine half way to running temp (~40C) I degreased it then power washed it. I have done this once before but then the engine was stone cold. Anyways, now the A/C compressor won't come on and the aux. fan stays on high. I've heard of the fan staying on like that after washing the engine but I've never heard anything about the A/C stopping.

Now I am in a pickle because two different people want to come and look at it tomorrow and I told them the A/C worked but now it doesn't. Please help, you guys are the greatest.

Thanks
David

Brian Carlton · #2 08-25-2006, 07:43 PM

No problem.

Take it out for a drive and get the engine fully warmed up and dried off. Run it for a good 20 minutes.

Return home and shut it down.

Start it up again and the a/c will work.

Ron Ragno · #3 08-25-2006, 08:03 PM

I agree with B.C.
2nd, take a look at the connections on TOP of the A/C compressor. It is very hard to see the connections as they are located just behind the clutch. Two things may have happened to this, dirty connections and or a loose or broken wire connection. Check it out. In my case it was a broken wire connection as well as general road grease. Give it a try.
R. Ragno

WANT '71 280SEL · #4 08-25-2006, 08:13 PM

I drove it home for 30 miles and it still didn't work. That was yesterday. Today it still is not working. I did just go out and look at it and it appears the temp sensor is bad. I removed one of the plugs and the fan went off, then I removed another and the compressor came on. I now recall something about these cars will shut the A/C compressor off at around ~120C, so I think the sensor failed saying the engine is at or over ~120 which is why the fan was on high while the compressor was off. The A/C is now working well and incase anyone else has this problem in the future, we'll know what it is.

Thanks
David

Brian Carlton · #5 08-25-2006, 08:18 PM

Good job.

Well, I'm -1 on this fix........

I figured that the water caused belt slippage and the system will immediately shut the compressor down with a speed differential between the compressor and the engine.

Do you need to replace the temp. sensor?

WANT '71 280SEL · #6 08-26-2006, 12:01 AM

Yes, but I will leave that up to the new owner if it sells tomorrow. Otherwise I will replace it.

Thanks
David