PeachParts Mercedes-Benz Forum - View Single Post

dmorrison · #12 07-11-2004, 10:00 PM

Your temp sensor is located on the top of the dash just above the 2 center vents. This unit has a tube that is connected to the fan housing. the AC fan is what pulls air through the temp sensor. From the sensor a hard plastic tube is connected to it. This tube goes along the underside of the top of the dash. At the glove box area the hard plastic tube is connected to a foam tube. On the right side of the glove box the tube again becomes hard plastic and goes downward to the far right side of the heater box where the fan is located. So if the foam tube is fine, the mechanical part of the temp sensor is OK.
What controls your fan speed is a combination of the AC control unit and the fan selector switch. The top button is the stage 6 or high speed. It by passes all imputs and runs the fan at the 6th stage. The middle white/clear button allows the fan to operate at stage 2-5. The lower button operates the fan at stage 1, no matter what the temp setting is at. In the middle auto position the AC control panel controls the fan speed and evaporator temp based on the input to the temperature sensor on the dash.
The AC units have been known to have cracked circuit boards which causes a break in the circuit. You may very well have this. Your AC board may very well be messing up. Do a search on AC contol panel.
check this site

http://207.210.95.34/~boostd/

I have not, knock on wood, had to mess with any of my AC control panles.

Dave

PS use the service CD you have adn check the temp sensor. YOu will measure the resistance based on the amient temp. Its in the service CD.