I have a 1991 190E 2.3 and have noticed that the fan clutch does not engage unless the A/C compressor is on. When the engine temp reaches about 100 degrees, the electric fan engages, but not the fan clutch. Now, when the AC compressor is on, both fans engage simultaneously in a cyclical fashion.

I have found a fan switch on top of the engine and jumped the connectors - and this caused the electric fan to engage. This is obviously the auxiliary fan switch. But I have no idea where the sensor or switch is that tells the fan clutch to engage at temperature.

Can anyone help me to diagnose this problem? At least I know that the fan clutch works, just not when the A/C compressor is off.

Thanks!!

 

VIN?

 

Hi, I'm new to this and feel a bit uncomfortable posting my VIN. But all of the 2.3's are the same mechanically from '87 - '93.

I'm just hoping this is something that I can fix. I know there is a sensor on the side of the water pump. But I don't know what it does.

Thanks again.

 

if you don't feel comfortable telling us more info about your car, then don't waste time reading wrong information that you might get.

i'll have to tell you that different engine designs got different systems.

[IMG]local://upfiles/1/E786854DDAEE4BA183420F31180CD50C.jpg[/IMG]

 

It's a 201.028.

 

Any thoughts? I just need to know what sensor or switch tells the fan clutch to engage at temperature...

 

Im a little confused about what your saying. The engine fan "free spins" until it reaches a certain temperature. It might be time to replace the electro-magnetic clutch tho. The aux. fans either engage at 100 or 105 degrees. I cant really remember, but I can look it up for you if you want.

 

Hi Dan,

The fan clutch works. I know this because it engages when the A/C compressor is in use. But when the A/C compressor is not in use, the fan clutch never engages - even if the car is over 100 degrees. However, in these situations, the electric fan comes on by itself.

Now I did check the auxillary fan switch on top of the engine and noticed that it was a blue switch and not a red. So someone may have installed the wrong switch. Regardless though, when I jump the pins, only the electric fan comes on. So somewhere else on this car is a switch or sensor that tells the fan clutch to engage at temperature (when the A/C is off). I just don't know where it is...

 

hi if your fan works when you short out switch conns .it is the switch at fault.To confirm this try putting the end in boiling water and see if the switch goes from open to closed circuit .in any case it sounds like the switch to me .

 

hi if your fan works when you short out switch conns .it is the switch at fault.To confirm this try putting the end in boiling water and see if the switch goes from open to closed circuit .in any case it sounds like the switch to me .