I have a 1998 Grand Cherokee 4.0l. The blower motor quit working a few times for a very short time but came back on after 5 to 20 seconds. Not working at all now on any speed. All speeds worked before. I checked the fuse under the hood and it's good. Any ideas?

 

It could be the blower bearings. Usually when the resistor cooks, it'll work on high only, unless the connector melts.

 

Bench tested the blower motor and works. Had power for about 20 seconds then quit. I show power to the red wire on blower motor. All connectors are good.

 

It's possible there is a thermal cutout inside the motor. IDK, I've never had a blower motor apart.

 

After testing the blower motor, it would only work when I hooked up power directly from the battery. Wheel was kinda stiff to turn. I replaced the blower motor and works good now.

 

Lucky you caught it before it did more damage. Usually what happens is the motor draws too much current and the resistor overheats. This can cause the wiring connector to melt and/or the resistor to burn out. The motor is a permanent magnet motor and should turn freely with a little lag as the poles turn past the magnets.