A/C blower motor runs on high speed only

Hi,

If the blower motor only works on hi, then the resister is likely the cause. I attached a portion of the wiring schematic below. Note, that power comes from fuse direct to the blower motor. The switch changes direction of the power for different speeds. From that point, a ground is provided to complete the circuit and run the motor.

If the switch is in the high position, the resister is bypassed and 12v runs through the motor. When you select the other speeds, power is routed through the switch, through a resister, and speed is controlled.

If you want to check the resister, simply see if there is continuity from pins where the lt green/white wire and yellow/red wire go to ground where black wire goes. Note that power should flow through these areas. (Don't get confused. Power doesn't exist between the yellow/red wire and the light green/white wire. It is between the black ground and each of them.

Let me know if this makes sense. LOL You could also check for power to the yellow/red wire and the light green/white wire. When the switch is in the low speed setting, the green/white wire should have power. On medium speed, the yellow/red wire should have power.

If there is power and the resister checks good, confirm the ground for the resister is good as well.

Let me know what you find or if you have other questions.

Take care.

Joe