jmlcolorado

So I had an issue a few months ago with the blower motor only working on the highest speed. I checked the blower resister and found it to have gotten hot and breaking loose the thermo couple. I soldered it back together temporally and it worked fine till I could get a new one.
I installed a new one from the dealer and all was well again for a couple more months.
This morning it seems to have been overloaded again as the same problem is occurring.
Is there a common issues in the switches somewhere that causes this to happen?
Pretty frustrating when I spend up to 6 hours a day in the truck.

jhenson

Possibly the fan motor drawing too much current and cooking the resistor......it's just a thought.

torquefan

When I replace a blown blower resistor, I usually measure the max current draw of the blower motor at the same time. If it's over 18 amps the blower motor gets replaced too. To me, a repetitive resistor failure is pretty good reason to suspect a worn motor.

Spooler

Yeap, blower motor is toast.

jmlcolorado

Awesome! Thanks guys!
Just for my own education, how do I test the resistance on the blower motor?

torquefan

Current draw is what I test on the blower. I use an amp clamp, and put the clamp around the positive lead to the motor, then read the amps with the blower running on high speed.

Jeff in TD

There have also been reports of charred wires at the ignition switch related to the blower motor, FWIW.

carl48

torquefan gave the only way to test the motor, the resistance of a bad motor does not usually change enough to tell. motor drag, bind, or armature rub is the most common cause of higher draw.