Free Auto Repair Advice by Professional Mechanics
Troubleshooting
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Blower Fan Works On High Speed Only
Blower Fan Motor Works On High Only
All cars are designed with a blower fan motor that pushes air through the
ventilation system. This air is processed by a series of vents to direct the air
to various positions. Example: heater, air conditioner and defrost modes. Most
blower motors are power by a basic electrical circuit that utilizes a multi
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.
Basic Heater Fan Circuit
Troubleshooting
- Turn the key to the "on" position (do not start the engine)
- Inspect system fuse
and replace if needed. Some cars utilize separate circuit fuses in the fuse
box, be sure to inspect all fuses and replace as needed.
- Remove the fan speed resistor component. This resistor is almost always
located in the heater plenum so it can be cooled by the air circulating
through the vents. After the resistor is removed inspect the resistor for
obvious burn marks at any point. If any area shows signs of extreme heat it
needs to be replaced. Also inspect the resistor connector for heat damage.
Reinstall with new and recheck system.
For exact specific repair procedures for any of the steps above visit our
online repair
manual page.
Troubleshooting
/
Blower Fan Works On High Speed Only
Check Manufacturer Specific
Blower
Motor Questions and Answers
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