it's a problem with the blower motor resistor,
If the blower motor randomly and intermittenly quits and does not work, chances are good the blower motor itself is faulty, if the blower motor does not work on all fan speeds from low through high, it most likely needs a blower motor resistor.
from what i have read it is the blower motor resistor it goes bad and only lets the fan run on high google blower motor resistor and read on
A blower motor that only works on high is normally caused by a defective Blower Motor Resistor Pack. DRL, do not have a clue.
The blower motor resistor has failed.The blower motor resistor has failed.
Probably a bad blower motor resistor
The blower motor speed resistor is burned out. The high speed function bypasses the resistor. The speed resistor is generally located near to the blower motor.
Usually the blower motor resister has gone bad.
If you are referring to the blower motor only working on the high speed setting, then the problem is the blower motor Resistor Pack is defective. Replace it. It can be the blower motor speed control switch but not likely.
When the fan is on high it does not run through the blower motor resistor. The low speeds don't work because the blower motor resistor is bad.
When you find out let me know I have same problem replaced blower fan and resisitor did not work. I have a blazer zr2 2002
The blower motor resistor pack is bad.