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Discussion Starter #1 (Edited)
I've been recently having trouble with my car, between my fan clutch and now my aux fans are not working. Thank you to everyone who has helped me with my previous posts about replacing a fan clutch and every other fix. I have a question now that I hope isn't to bad...

My Aux fans wont turn on, at operating temp or with AC full blast. I opened up the fuse box and pulled of the covver and exposed the few relays in the back. There are two yellow ones and 2 black ones and a green one. Between the two yellows and the front back (i think its "b") there is a green one. When i pull out the green one and shake it - it rattles. Is it bad? Is that why my aux fans dont turn on?
 

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The aux fan won't come on until either the AC pressure gets over about 250 psi, or the radiator temp get hot (I don't know temp).

As such, you may not see this happen at idle. How do I know, it drove me crazy also.
 

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2000 C230 Kompressor Special Edition
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Green relay is a multifunction relay, but not for aux fans. I changed mine when I did a complete fuse and relay change.

Need to know what year your car is.

The aux fan relay is inside the wheel well on the drivers side. You have to turn the steering wheel all the way right and remove the front inner fender trim.

I changed mine, and it made my fan start up smoother sometimes, and it made my automatic car shift better.

Is your coolant temperature gauge working? What is the average temperature where you live?
 

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Discussion Starter #4
so the green relay isnt worth replacing? what does it do?

Also sorry its a 99 c230k. I live in Pa near philly, about 40 miles away. So this summer has been a hot one, mainly 90s. The thermostat inside the car next to my fuel gauge usually runs around 80 when moving, and 87 when stopped.

I'm just confused as to why these fans wont turn on????:confused::confused:


edit: Also, bachusaattackus and marvinstockman - Thank you for replying, and helping me also with my fan clutch. Runs like a champ!
 

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1997 W202-C180 Classic, smoke silver metallic, Lowered
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80ºc-87ºc sounds normal,
Mine sits just below 80ºc when the outside temp is about 22ºc
Never really see the fan on.
 

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1999 C280
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The fans will not turn on when at the 80-87 temp range. Mine dont kick on til just over 100.
Like others have said, this is normal.

Mark
 

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Discussion Starter #7
i guess the only reason it worried me, is my car takes forever to cool down. Ill park it and 2 hours later its still close to operating temp when i turn it on. I thought the electric fans usually cool that down quicker?
 

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1997 W202-C180 Classic, smoke silver metallic, Lowered
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They do retain the heat pretty well,
I prefer this to what my Audi does as it takes ages to warm up and not so long to cool down,
Rather have an engine within operating temp
 

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In you driveway, put cardboard in front of the radiator. Turn on AC and all other accessories, lights, rear defroster, etc. Your aux will eventually come on as temp goes up.

Finally, be very glad that your car takes a long time to cool down. A hot car would actually last forever, well almost forever, as you'd never have to deal with cold starts and thick oil.
 
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