The blower motor stopped working. No matter which speed I select, it does nothing. What is the most likely cause? I bought a new motor and started on it yesterday. I've almost got it out, but the power wire is burried and looks like it will be next to impossible to get the new power wire routed. Any tips on troubleshooting? How do I check to see if the switch is bad?

 

Probably the sealed bearing in the blower moter got tired and is now very hard to turn drawing a lot of juice. You didn't mention if it had blown fuses in the past or if some one had put a higher rated fuse that cooked the wires. The easiest way to test is to cut the wires and run positive to positive on your battery post and ground to engine block. Aligator leads work great but if your wires are now cooked and you don't want to reroute thru your wire harness, you might even short out your new motor. If you try to hook up the easy way, now is to install the new fan motor, save the old plugin if thats ok, cut the leads long enough so you can splice new wires, buy a good togo switch, run positive in thru firewall, install togo somewhere, run wire direct to positive battery post, & then splice new wire from negative lead to frame or engine. With the absence of speed control, the fan will run on high. Thats ok, now you are in charge of turning fan on more importantly off.

 

I need to make a correction. I didn't read your question carefully. My answer refers to a radiator fan motor, but the answer is the same except direction of wiring.