I have a 2003 Ford F250 SD Pickup truck, with a light bar setup and controls in the cab. For whatever reason, I CANNOT get me blower motor to work for my AC or Heat?! I have replaced the resistor, the blower motor, the control knob in the dash, just about everything I can think of. It simply will not run? Could it be a ground issue with the Lightbar setup & console? If anyone has any experience, could you tell me how I could troubleshoot this problem? I have some knowledge of electrical but I am no expert for sure. This is driving me crazy and I can;t use the truck in rain, high heat, and cold weather. I also have no defroster. Thanks for any help or advice!! I would bring it to a local garage, but I am currently unemployed and money is tight.
Somewhere either + or ground to the motor isn't making contact. Run a test wire from the red terminal of the battery to the red terminal of the blower motor without unplugging the connector. You can poke the tip of the wire into the metal terminal of the RED only. It will spark a little when the motor takes the amp load. If there is a good ground to the motor, it will turn on. Update us on what happens.
If it runs after the test, check the plug connector at the resistor block for corrosion on the terminals and clean the metal contacts with a tiny screwdriver or pocket knife as necessary. For sure you checked the fuse.