Two temp, adjustable, dual fan, dual speed controller circuit. | Ford Explorer Forums - Serious Explorations

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Two temp, adjustable, dual fan, dual speed controller circuit.

1998rollover

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1998 Mountaineer
Here is a fan controller circuit, drawn up by Don Doersch, a retired US Navy radioman. It has adjustments for high and low speed. It gets two speeds from two single-speed fans by switching them between series and parallel connection.

http://www.flickr.com/photos/27748767@N08/5578415649/

I cleaned up the scan and re-typed the parts list which was originally done on a typewriter.

If you want to use a pair of fixed temperature switches, simply cut off everything past the two transistors, Q1 and Q2. (The left half of the circuit, including the transistors.)

Alternatively, the relay section could be modified to control a dual speed fan instead of a pair of single speed fans.

It would also be possible to change it to completely cut out the fans when in overdrive, including a "Too bleeping hot!" override sensor switch that disables the overdrive cutoff so the fans will run while cruising down the freeway.

My plan for this is to put the electronics in a box and connect the relay sockets to it with a multi-wire plug. The sockets I got connect together in a row and the relays have metal mounting tabs.
 






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