The blower fans on these cars run very quietly on all but the maximum setting- ensure that the fan is really not working first by holding your hand in front of the vent with the fan on low and checking that is it not moving any air. Replace the resistor pack.
Check the blower resister
The heater motor speed resister is burned out.
Possibly
heater resister is bad
Replace heater motor resistor.
The blower motor speed resistor is burned out.
YOUR BLOWER RESISTER IS BAD
Your heater switch may not need to be replaced. The heater high position is controlled by a fuse under the hood. Until you find the fuse and replace it, your new switch will not work. JRR.
If you are saying the Blower Motor only works on high, then your problem is a defective Blower Motor Resistor Pack. Replace it.
Replace the blower motor resistor.
A common problem is that the heater resistor/ circuit board is defective and need to be replaced. The main symptom is that the heater fan with not run on the three low speeds but will run on high.
If you mean the fan works on high only it's the blower motor resistor.