Step by step repair guide on how to repair a blower motor that only works on
the high speed setting. This article pertains to all non climate controlled vehicles.
Difficulty Scale: 4 of 10
Tools and Supplies Needed
- Socket Set
- Screw Driver Set
Begin by parking the car on level ground in park with the emergency brake on.
- Turn the key to the "on" position (do not start the engine).
Inspect system fuse and replace if needed. Some cars utilize a separate fuses to
control lower fan speeds in the fuse box, inspect all fuses and replace if failed.
- Locate and remove the fan speed resistor component. This resistor
is almost always located in the heater plenum so it can be cooled by air circulating
in the system. After the resistor is removed inspect the resistor for obvious burn
marks. If an area shows signs of extreme heat (burned) it needs to be replaced.
Also inspect the resistor connector for heat damage. Reinstall with new and recheck
A blower fan motor pushes air throughout the ventilation system. This air is
processed by a series of doors and vents to direct the air to various positions:
heater, air conditioner and defrost modes. Most blower motors are powered by a basic
electrical circuit that utilizes a multi speed resistor or a solid-state resistor
to control different fan speed modes (low, medium low, medium and high). If the
resistor malfunctions it may lose one or more of the lower fan speed settings.
Article first published 2016-02-03