1989 190E 2.6L gas/auto

When the engine is running about normal temp (80-90C) the electric fans dont work. When the A/C is switched on, the fans turn on, but slow. If i unplug one fan, the other one speeds up to what seems to be full speed, the unplugged one obviously stops. After plugging it in, the other fan slows again. The green 2 pin sensor above the 6th cylinder is brand new replaced. I believe it tells the computer what the engine temp is.

Please chime in about what is normal. My suspicion is that the A/C turns the fan on when head pressure is good and when the engine is above 100C, it then cranks up the fan speed to full.

Lets hear your version?

You have a two-speed electric fan setup. The low speed setting is triggered by the air conditioning, based on a certain pressure reading. I don't know what that pressure reading is. The high speed setting is triggered by coolant temperature reacing 105 degrees C.

I don't know about one fan speeding up from the low setting when the other is disconnected. Perhaps that is a safety mechanism to help keep the car from overheating with the a/c on?

Ok. I checked the volts with both fans plugged and running. 8VDC. with ac on. I replaced the resistor with one from another car, it did the same thing. The old resistor was cracked and it was smoking from heat, it was blazin hot. I put the 2 wires together on 1 post and the fans run at 11.5VDC and they are really going fast. Quite a bit louder.

Will any harm come to the fans at this voltage?

WHat is the reason behind the resistor anyway?

I am trying to get it to pass emission testing in Texas. Cooler is better right? Ive got high nox and high hc.

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