Elec. fan runs when cold in A.M. 1990 300E??

[milhan]

Every morning, when I start my car to go to work, the electric fan turns on high. The outside temp in the a.m is usually between 60-70 degrees F. So its not exactly desert tempertures. After driving about a mile, the fan will turn off. After work when the temps increase to 85 degrees, the fan doesnt turn on upon start up. I dont have the A/C, or the ECON switch on. Any idea why this is happening? I worry when it gets below freezing this will happen, and my car will never warm up. Thanks 1990 300E. 3.0

[sixto]

Do you see or hear fans? If you hear fans, you might instead be hearing the air pump warming up the catalytic converters.

Sixto
... stay tuned

[milhan]

This sound didnt happen last winter?? I will check this out, but Im pretty sure its the radiator fan. Didnt know about this air pump thing

[sixto]

Did you work on the clutch fan in the last year?

Sixto
... stay tuned

[milhan]

No I havent touched anything. This just started. Is there maybe a coolant pressure switch or something that could be bad?

[brabus3.6]

From the sounds of it you have air-con but do you have the * switch or the EC switch? If you have the * switch ON or the EC switch OFF than it could be the fans coming on due to the AC being on and not being needed once the car has warmed and the viscous fan clutch has started locking. Just a possibility. If this is it than putting the * switch OFF or EC switch ON will prevent this noise.

[milhan]

I do have a EC switch which is on and the ac switch is off. Even when I turn everything off, it will do it. I just filled the overflow bottle to the top with coolant/water mix. I started it, and no fan!!!!! I see a sensor in this bottle, and Im wondering if this is not covered in water, the fans will turn on thinking its low on coolant???

[sixto]

The reservoir sensor is only there to turn on the yellow radiator warning light in the dash. It's not hooked up to the fans. The fans cool the radiator, not the engine. If you're low on coolant, no amount of air will cool the engine.

Under some conditions the clutch fan will come on full tilt during a cold start. IIRC after a few seconds it should disengage and then only come on when it's 105*C or so at the radiator. Maybe that's what you're hearing.

Sixto
... stay tuned

[softconsult]

So how about this?

Go out in the morning. Open the hood. Start the car. Look and see what is spinning. Is it the two fan's in front of the radiator? Is it the viscous Fan?
Or is it the air pump, just above the alternator on the passenger side of the engine. That air pump is my bet. Perfectly normal.

Steve

[milhan]

The last two mornings- NO fans or pumps??? I filled my radiator bottle cuz it was low. Did this cure the problem???

[milhan]

well I thought my problem was over, but today, it did it again. In the morning, I checked the noise upon start up. Both aux fans were running on high. Ran for about 2 minutes than turned off???