The blower motor is one of the most critical components of an HVAC system. Located in the air handling unit, it is in continual operation while the unit is on regardless of whether the unit is cooling or heating. Some systems may also allow for the motor to continue to operate at all times whether or not the rest of the system is active. If there’s an issue with the blower motor, you’re simply not going to get air.

Blower motors are resilient and do not often experience unexpected failure, but they do need some regular upkeep to maintain their proper function. The good news is, they can not only be maintained but also repaired without advanced technical knowledge. In today’s post we’ll walk you through the basic checks you can perform to determine if your HVAC blower motor repair is going to be a relatively simple DIY job.

  1. Checking The Power.
    As with most electrical or electronic devices that are completely failing to operate, the first step in the troubleshooting chain is to make sure they are receiving incoming power.

    If power can be verified to the unit but the motor is still not functioning, the next stop is to take the cover panels off the motor and check it directly. The presence of lots of dirt and debris is often an early sign the motor has shorted, as are the bodies of dead ants (which can create a short if they are positioned in just the right way). Simply cleaning the motor of these things may cause it to function again.

  2. Checking The Windings.
    If debris is not the issue, it’s time to get out the multimeter and check for AC voltage across the motor’s contacts. The windings should then be checked for resistance (ohms). A reading of zero indicates a short in the winding, while an infinity symbol means there is an open in the winding somewhere.
  3. Checking The Capacitor.
    If the motor windings seem to be find, move on to the capacitor, which generates needed torque for the motor. It is most likely connected to the two brown wires coming from the motor.

    Ensure that power to the unit has been turned off and discharge the capacitor before testing using your meter. The easiest way to test the capacitor is to use a specialized capacitor testing tool, but if you don’t have one you can once again check the resistance using the meter. If you’re using a capacitor tester, the microfarad reading should be within 10% of the rated capacitance. If you’re checking resistance with a meter, connect a lead to each of the terminals, and you should see the number start at zero and slowly climb to a very high amount.

  4. Getting It Done.
    Once you know which component has failed, you’ll know what needs to be replaced! One final helpful tip is to clean out the blower motor area before replacing the cover panels; even if dirt and debris wasn’t the cause of the problem, it will eventually cause another failure if enough is allowed to accumulate.