1988 300CE Auxilary Cooling Fan Problem

[Just Carol]

I am a newbie, so please forgive me for asking what may appear to have been answered many times. I replaced the water pump, thermostat and belt on my 1988 300CE. I did this because the temperature gauge had begun to "creep" higher than what was normal for this car. When I restarted the engine, the temperature again began to climb above the normal range for this car. After replacing the above listed components did I notice that the auxilary fan was not turning on! It is possible that this was the original villian of the rising engine temp. I have replaced the relay, checked and replaced fuses (none had failed) and have replaced the resistor on the left frame rail. I can make the fan run at low speed with the key in the on/run position by ground the brown/blue wire at the Receiver Dryer and at high speed by disconnenting the 2 pole switch at the top of the head. What am I missing