Sounds like a bad blower motor resistor block.
usually the blower motor resistor pkg. located on or near the blower motor
The blower motor speed resister is burned out.
The blower motor resistor is bad.
Normally when some speeds work and others don't, the problem is a bad, Blower Motor Resistor Pack. You will find it somewhere near the blower motor.
Not always, but 99% of the time this is a sign that the Blower Motor Resistor Pack is defective. Replace it.
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.
change the blower motor resistor . this controls the speeds . thanks paul
Probably the blower motor speed resistor is partially burned out.
Probably the blower motor, wiring to it or control switch
The blower resistor controls the speeds of the blower motor Hi-resistance lower motor speed Lo-resistance higher motor speed
Blower fan resistor controls electric current to the fan motor to maintain different speeds.
If you have no blower speeds at all check the fuse, then check the blower motor switch and electrical plug for a melt down situation, then check the blower motor itself.