Can the Positive and Negative Leads be Switched to Reverse Fan Rotation on Radiator Fan # D18914

Updated 09/04/2012 | Published 08/31/2012

Products Featured in This Question

Derale 12" Dyno-Cool Curved-Blade Electric Fan - 810 CFM

(7)

$72.44

Derale Adjustable Fan-Control Thermostat with Radiator Hose Probe

(6)

$58.07

Derale 14" Dyno-Cool Curved-Blade Electric Fan - 1,230 CFM

(7)

$101.12

Question:

I have a Derale 18914 larger version of the 912. I want to reverse the positive and negative leads, reversing the current flow. Will this damage the fan motor? Will this reverse the rotation of the fan motor? Also, I want to pulse-width modulate the fan voltage to control the speed. Will this work with this fan motor at a PWM rate of 20KHz? What is the minimum voltage at which the fan will begin to rotate?

asked by: Dave C

Expert Reply:

The Derale electric fan, # D18914, is a pusher or puller fan. To reverse the rotation, you would switch the wire leads. I tested it myself just to be certain and sure enough when the leads were switched the fan spun in the opposite direction.

I do not think you will be able to use a PWM system with this fan. You would need some sort of control module and the fan is not designed for pulses of voltage as it will not sustain operation unless a constant 12 volts is applied to it.

To control the fans operation at certain temperatures you can use an adjustable thermostat like # D16769. With this thermostat the fan will come on at a pre-set temperature from 32 to 240 degrees.

expert reply by: Michael H