Car Heater Repair Tips: Fixing a Blower Motor

Restore multiple speeds with a simple replacement part

Restore multiple speeds to your auto heater/air conditioner blower by replacing a resistor module. It’s a simple, quick change-out.

By the DIY experts of The Family Handyman Magazine

Restore multiple speeds to your heater blower

Most car manufacturers use a series of resistors to make the heater blower motor run at different speeds. And when one or more of these resistors burn out, you're usually left with only one blower speed—high. The resistor module is easy and inexpensive to replace. It's then typically installed in the ductwork, near the blower—either under the dash or under the hood. (Refer to a service manual to locate yours.)

Purchase a new resistor module at the auto parts store (usually less than $25). Disconnect the electrical connector. Remove the screws, and swap out the resistor module. Reconnect the electrical connector and you're back in business.

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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • 4-in-1 screwdriver
  • Nut driver

You may also need a trouble light.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

  • New resistor module