A/C blower motor

[Packrat]

99 buick. The blower motor stops blowing, if I tap on the plastic cover on the fire wall, or hit a bump, it will blow fine, but then slows down after a few minutes. Tap on the cover again and it starts blowing again.
I checked the wiring going into the plastic cover and it it fine.
I don't know what is under the cover, if it is the motor or what, but tap on the cover and it starts working.
Anyone ever have this problem?

[drivera1]

I have had this problem with my Bonneville, and it was a burnt connector . You should disconnect the harness and check. You can get this connector from your local dealer.

[pcv]

Check the connections and ground to the blower motor. If they are okay, replace the blower motor.