Mercedes-Benz 1995 E-320 wagon. Auxiliary fans not going on at high temp. Told it was relay. Then found out there is a stage one and two. Don't know what to do.
The cooling fan relays could be the problem but there are other components involved.
Stage 1 and 2 are for each fan, stage 1 should be for one fan and stage 2 should be for the other fan. You should check fuse number 7 and fuse F22 #1 and F22 #2 in the Aux fuse holder in the fuse box located in the engine compartment on the left side.
The relays control the fan operation but they are controlled by a coolant temperature sensor for the computer not for the gauge, and a fan control pre-resistor relay module. The fuse/relay box is located in the left side of the engine compartment. The relays are K9 (low speed fan), K10 (high speed fan).
The low speed fan is controlled by the Duel Function Pressure Switch on the receiver drier. High speed is activated directly by the coolant temperature sensor, via relay (K9) and the ACC control unit, at approximately 224°F (107°C). When the pressure or temperature drops below preset values, fan operation discontinues
The system should be scanned by a professional; he would be able to spot where the problem is through the scanner and a volt meter.
Let us know how you make out.
Last edited by TechHelp2 (7/10/2010 5:44 PM)