i have a 1991 cherokee sport and the blower fan works when ever i hit a hard bump.i pulled the resistor and did a continuity test and it was fine. did a volt test on the wires for the blower and got 12 volts out of it when turned on and 0 when the switch turned off. pulled the blower fan out and it spines but a little stiff. i plugged in the blower fan while it was out and it worked fine went from high to low speeds gust fine. then i put it back in and it stopped working then. i pulled the resistor out but left it plugged in and the fan worked again. when i turned it off and then back on it stopped working .any advice will help. thank you

 

Check for power and ground at the blower motor plug when it stops working. If you have them both, replace the blower motor. If not, work your way back from there. Don't over think the situation. I've tested and changed many blower motors and a lot of them that went bad can be tapped with a rubber mallet or the palm of your hand it can come on for awhile. Then when you turn them off they may not work again until you either hit it or you go over a bump. Some Cherokees had a problem with the plug on the back of the actual switch but start at the blower motor plug and work your way back from there.

 

thanks for the info