Ok guys, I'm asking this question for my Mom's 97 GLE with 90k on it. It seems like constantly the aux. cooling fan is running. The heat gauge reads fine, and I've kept the antifreeze changed out every 30k or so.

Car runs fine but it seems like the extra fan wants to run an awful lot. I've noticed that after the car warms up that turning on the A/C will kick on the 2nd fan every time, immediately.

Nothing is overheating according to the gauge, could I be looking at a faulty CTS (coolant temp. sensor?) When the engine has been idling a few minutes in this hot weather, sometimes for 30 seconds or so after starting to drive you do get some knocking.. (knock sensor replaced last Fall, and it's only for a short period after idling a while in the hot temps).

Any ideas?

thanks!

 

does it run when the car is off? if it runs when the car is off, it needs more coolant, try that first it should work, if its not that its the thermostat. if not that then you have a fawked radiator.

lol just add coolant! make sure it flows like a river

 

No, the fan doesn't stay running when it is shut off.. Coolant is fine. Where does the car get the reading for the dash heat gauge?

 

it seems normal to me. my second fan ALWAYS goes on when i turn on the A/C

 

You have a bad fan relay. If the engine coolant temp sensor was faulty and always telling the ECU that the engine was hot, you'd have cold starting issues. Both cooling fans are always on when the A/C compressor is running.