It is probably the rheostat located above the passenger foot area. Remove the plastic cover and look next to the blower motor. It has two wire connectors attached to it and is held in with two 8mm bolts. You can pick one up at a junk yard for a few dollars.
sounds like the blower motor resistor is out on the lower speeds.
replace the blower motor switch
the blower resistor controls the fan speeds
blower motor resistor is burned out
Your blower switch sensor is out. Replace it!Then all the speeds will work
The blower motor resistor pack is bad.
If it has only high speed, the blower motor resistor has to be replaced to get all speeds back.
When you beat the blower motor, you are probably shaking the blower resister. The resister is what controls the blower speeds and is probably bad or loose.
If the blower works on slower speeds only I would suspect the high speed blower motor relay (under the hood in the power distribution box) or the switch itself. The blower speed resistor is working if all the slower speeds work.
Only for the high speed. The lower speeds are controlled with the use of a blower motor speed resistor.
need new blower motor...
The front blower should have a resister to change the speeds. It is usually mounted close to or on the back of the blower motor.