Hi there, just a quickie. A while ago the cooling fan on my 190e 1989 was not coming on at all no matter what temperature. I understand that it is supposed to kick in at around 100 degrees. I was advised to change the (dont know what its real name is) temperature sender unit!! You know the brass thing that screws in on top of the engine. Well I have done that now and it still isn't working. I have tried touching the contacts together and the fan works when it is given direct power. Are there any other things I should check for? Thanks.

First, do a search on "aux fans" and you'll see lots of posts on testing these fans. Then see what questions remain unanswered ...

__________________
Steve
'93 400E

Your model is one with which I am not familiar, but I would expect that the sensor which controls the fans is on the radiator, not the top of the motor, since its job is to judge whether the coolant has been adequately cooled before it goes back to the water pump to be sent back into the motor.

Do you mean the contacts on the thing you replaced?

However, how is your AC working? There are two things that trigger your fans. The temperature switch (which you already changed) and the pressure switch on top of the AC receiver/dryer. You can also touch both contacts on that swicth to see if the fans start working. If you have low freon in your AC, the fans will NOT work. As far as the 105 or 115 degree (the number is on the side of the switch) temperature switch will NOT operate the fans unless the coolant in the engine reaches that temperature. There is also a resistor, low speed, high speed, so do a search. It has been discussed before...

__________________
J.H.
'86 300E