Aux. Fans
 

Spring fever
I have never heard the aux. fans working in my car. how can I test them to see if there working and what temp are they supposed to come on. I heard there supposed to run when you turn on ac. true or false? 94S

I have heard the same thing about the A/C. Iam not sure about your car, but I was told that with a 450sl. Pull the single wire of the water temp sensor, front of engine, and ground the wire to the engine. Key on. Hopes this helps.

THE FANS WILL ONLY COME ON AT 160 DEGREES WITH THE A/C RUNNING

My understanding is they come on when either the engine gets up to about 105 at fast speed, or when the aircon is turned on, but spin at a slower speed.

You can trick the temp sensor by unplugging and shorting the cable, which makes it work as a closed switch. Mine didn't work originally but a few smart taps on the spindle of the fan and a dose of WD40 did the trick. I drilled a tiny hole in the fan cover and sprayed through that, and sealed up afterwards.

I assume you mean a 94 S class? If so, I believe low speed is tied to the A/C operation and the cut-in point for high speed is around 107C.

Check the table in 'blue' in MENU#18; it shows the temp and pressure 'trigger' points for the aux fans.