The problem is most likely a bad Blower Motor Resistor. The High setting bypasses the resistors and connects directly to the battery. The lower speeds use the resistor to lower the voltage. Where is it?: Usually the reisitor is found behind the glove box to the left. Also the wires from the control knobs should lead to the resistor.
The heater motor speed resister is burned out.
Idle is not adjustable. You have a electrical or vacuum issue that needs diagnosed.
It is not a fuse problem. The HVAC resistor pack is defective. Replace it.
heater resister is bad
2004 Chevy express van, heater has no high speed, at one time the blower stayed on even when the ignoton was turned off therefor draining the battery,
win the speed inferno challenge.
The blower motor speed resistor is burned out.
Replace the blower motor resistor.
Need for Speed High Stakes - 1999 VG is rated/received certificates of: Australia:G USA:E
Check the blower resister
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.
The blower motor speed resistor is burned out.