Question about Mercedes-Benz 190-Class

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Aux fan not cutting in when o/heating 1989 190E 2.6Ltr. Fans operate when tested.

Both fans operate when tested but eng. aux. fan won't cut in when o/heating.

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  • James Park. Feb 25, 2012

    Viscous fan is O.K. Aux fan should come on with-out a/c operating.
    Have had temp. right up on scale when testing.
    Does aux fan operate with-out a/c?
    Fans are wired seperately!

  • James Park. Feb 25, 2012

    Need to know if aux fan operates when eng o/heats (repeat ENG. aux fan not a/c fan)
    Both fans in front of radiator are wired independent of one another .



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  • 166 Answers

Your vehicle should have a viscous fan clutch for controlling the engine temp from overheating. The auxillary fans in front are used when the a/c is on. I would start by spinning the engine fan or viscous fan by hand when the vehicle is off. The fan should show resistance when you spin it. If it doesn't and it just free spins then the viscous fan clutch is bad. Let me know what happens when you spin the engine fan and also exactly how high does the engine temp get. Does it reach the red mark?

Posted on Feb 23, 2012


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Based on limited information so far, it sounds on the surface to be the TPS (throttle position sensor). This component controls the idling speed of the car under all conditions (cold, warm, AC turned on). Unfortunately, the component is purely electrical and the only way to repair it is to replace it.

Posted on Jun 20, 2011

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Just a shot in the dark, But did you or some one else remove the thermostate?
If so put a new one in this will let the car run fine in the summer but cold weather the car cant get warmed up.

Posted on Nov 28, 2010

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SOURCE: engine cooling fan wont work

check the temp sensor on the engine for the cooling fan.It should be around the thermostat housing or on the side of the head.

Posted on Feb 07, 2010

  • 1 Answer


I had a similar problem on my 190E 2.3 1992.
I solved it replacing the relay multi use with 5 pin connection. It's cheap and probably will resolve it.

Posted on Jan 23, 2010

  • 6826 Answers

SOURCE: ac not working cuts on and off when aux fans turn

i assume u r refering to the cooling fans,,, if this is so the freon is low ,fans come on and lower the high side ,there fore lowering the low side and the low side switch cuts it off and on,,charge it up

Posted on Jun 30, 2009

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