Your car's blower motor is not only necessary for the operation of your air conditioner. Without a functioning blower motor your engine runs the risk of overheating. If you hear that the blower motor is operating but don't feel any air flowing through the vents, the problem is with the airflow controls [source: RepairPal]. If the blower motor isn't running you should:

  1. Use voltmeter or ohmmeter to check for a blown fuse. If you find one, replace it.
  2. Start car and see if blower motor works. If fuse blows again, check for loose circuits.
  3. If the circuits are in good repair but the blower motor keeps blowing fuses, replace the blower motor [source: You Fix Cars].

If your engine's working fine but the blower motor isn't, you can test the blower motor to see if it needs cleaning or repair. Here's what to do:

  1. Disconnect car battery.
  2. Detach the blower motor from its connector.
  3. Unscrew all the screws on the blower motor. Place them in small container.
  4. Locate the retainer clip in the center of the blower wheel. Disconnect it from the motor shaft and set aside.
  5. Clean out any debris from the motor.
  6. Clean the blower motor with an electrical-parts cleaner.
  7. Oil the bearings.
  8. Check that the blower wheel spins freely and all the other parts are operating properly. If a part isn't working properly, clean and oil it, and test it again [sources: PartSource].

If you can get the blower motor working again, reinstall it. If not, you'll have to buy a new blower motor.