280sel 4.5 auxiliary fan not running - Mercedes-Benz Forum

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post #1 of 2 (permalink) Old 05-24-2014, 09:00 AM Thread Starter
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Date registered: May 2013
Vehicle: 72 280SEL
Location: NW burbs of Chicago
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280sel 4.5 auxiliary fan not running

Hi all

I have a 280sel 4.5 and the other day when in bumper to bumper traffic with 90 degree temps and I noticed that the car was running a little hotter than it ever had in the past. I got home and found out that the auxiliary fan was not switching on when I turned on the AC. I thought that it should go on whenever the ac is on even though it had not reached 212 degrees. I checked the fuse and it looked fine so I grounded the wire on the sensor and the fan would run.

After this I thought it must be the sensor so I replaced it. It still did not go on with the ac running. then I tried to get the engine to 212 degrees in the driveway with the ac on but it never got close so I do not know it it will work if it gets that hot.

I thought that if I could get it to run when grounded that ment the fuse and the relay were both good and most likely it was the sensor if that is not true please someone clue me in. If I cannot get it to run I might just put a switch in the car and run it manually.

Any ideas on what I should try next?

1972 280 SEL

Last edited by Geen; 05-24-2014 at 09:59 AM.
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post #2 of 2 (permalink) Old 05-25-2014, 08:49 AM
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Date registered: May 2003
Vehicle: 2012 Focus SE
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I would still check the relay, they're pretty inexpensive, so might be worth swapping out just to be sure.

Felicita e un bicchiere di vino con un panino.
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