I changed resistor part under glovebox but did not fix.

Fan and defrost work but only on speed 1 (takes forever to heat car)

So it's not resistor. What else should I do /check?

Occasionally when I hit pothole everything starts working again.

2001 max SE 20th

Thx

 

Try hitting on the blower motor when it is running and see if that makes it speed up. If it speeds up, replace the motor.

 

You can pull the harness that plugs into the motor and hookup a voltmeter to the end. Check the voltage at the various speed setting to make sure there isn't a problem with the climate control box. If that tests fine, the next thing is to make sure the contacts on the blower are in good shape. It also wouldn't hurt to remove the blower, spin the blower wheel by hand to make sure it spins freely. If it doesn't, chances are the blower motor is going bad. While you have it out, you can look for evidence of the blower wheel making contact with anything as well.

S