2004 Chevrolet Avalanche fan isn't blowing

Fan or blower for ac/heater is not blowing. Possible causes/fixes.

If not blowing at any speed setting, it’s the switch or the wires/connectors or the fan motor. If you apply 12V to the motor and it runs, the switch is likely bad.

Under the dash on the passenger side there is access to the fan. Access this area and you should find the resistor pack that controls the fan speed. Unplug the fan and you should be able use a jumper wire to apply 12 volts to the fan itself. If the fan then runs, your resistor pack needs to be replaced. If the fan still does not work by jumping it…then the fan needs to be replaced.


I would check the fuse feeding the blower motor first.
If that fuse is blown, replacing it may restore operation for the short term.
Sometimes, a blower motor that is starting to fail will take out the fuse a few times before it actually fails outright. I’d also pull the cabin filter and check for obstructions in the fan cage area and see if it spins freely with your hand.

Turn the ignition on.

Set the fan speed to high.

Reach under the dash, passenger side, and rap on the blower motor with the handle of a screwdriver.

If the blower works when doing this, replace the blower motor.


Doesn’t a bad resistor still allow the fan to run at its highest speed?

Not all of them. I have a Dakota that has lost the highest setting, but all others work.
I only use the truck once in awhile and it has 300.000 miles on it. Unless I lose all the speeds, it’s fine with me.


Usually, the highest setting is through a relay with no ballast= full voltage applied to motor. The relay is often located on the same card as the ballast resistors.