1987 190 Dt

Would anyone have an idea how I would make the auxillary cooling fans start as soon as the A/C compressor starts? I tried bridging the connections on the switch at the dryer, but the fans run continuously w/wo the compressor. I'm just rying to help cooling efficency.

Any help is appreciated. Thanks!!

I believe the fan is energized through grounding. In other words, one side of the fan is hot all of the time and the temp switch grounds the fan when at the right temp. You could use a relay that would energize when you turn on the A/C and the switched tepminals of the relay would be the grounding connection for the fan.
Before I did anything, I would use a test light to ck that the fan is hot all of the time.

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My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.

You could tap into the connection at the low pressure switch to get your trigger to the relay to turn on the fan.

I made the connection today. Probing around i discovered that connecting a wire from the freon pressure switch to the auxiliary fan switch would ingage the fans with the compressor.

Thanks