Troubleshooting AC Blower Motor on Ford Super-Duty After Replacing Fuse, Relay and Resistor

Question:

trailer harness got damaged caused short. now blower motor wont wk. replace fuses , resitors , relays and still no power to motor. connect motor to battery works fine. what else can i check.

asked by: Chris

Expert Reply:

Since you have done troubleshooting to confirm that the blower motor itself still works when directly connected to the battery, and you have replaced the fuse, resistor and relay, I would carefully check the wiring to the motor in case the wiring itself was damaged by the short. You can also check the connector on the motor wiring to make sure there is no heat-related damage to the connector from the short-circuit.

With the truck running and the AC turned on apply a circuit tester like # PTW2992 to the contacts on the motor wiring plug. If power is reaching all the way to the connector but the motor does not operate I would suspect the connector is damaged. Since you already know the motor itself works, if power is reaching all the way to the motor's connector then the connector would have to be the issue.

expert reply by: Adam R