How to Clean a Squirrel Cage Blower Fan

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Things You'll Need

  • Phillips screwdriver

  • 5/16-inch nut driver

  • Adjustable wrench

  • Garden hose

Furnaces and air handler units use a squirrel cage blower fan to force air through ductwork and out of diffusers mounted to the walls, floors or ceilings of a house. When the squirrel cage runs, debris that passed through the filter clogs the thin spaces between the cage's blades. This reduces the air pushed through the ductwork and forces the fan to run for longer periods. Cleaning debris out of the squirrel cage will increase airflow and reduce utility bills.


Step 1

Turn off the circuit breaker for the line that supplies power to the furnace or air conditioning unit.

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Step 2

Remove the trim cover surrounding the open side--opposite the motor--by turning each screw counterclockwise with a Phillips screwdriver. Use a 5/16-inch nut driver if the cover is secured with self-tapping sheet metal screws. Place the screws in a safe location.


Step 3

Pull the trim cover from the side of the furnace or air conditioning unit.

Step 4

Loosen the retaining bolt on the end of the squirrel cage by turning it counterclockwise with an adjustable wrench. Slide the squirrel cage from the furnace or air conditioning unit.


Step 5

Rinse the squirrel cage outdoors with forceful water from a garden hose. Set the squirrel cage in direct sunlight--away from dusty areas--until dry to the touch.

Step 6

Slide the cleaned and dried squirrel cage over the motor shaft. Tighten the retaining bolt with the adjustable wrench.


Step 7

Push the trim cover against the opening for the squirrel cage. Turn the trim cover to align its holes with the holes in the side of the furnace or air conditioning unit. Install one screw in each trim cover hole. Tighten the screws with a Phillips screw or a 5/16-inch nut runner to secure the trim cover.

Step 8

Turn on the breaker to supply power to the furnace or air conditioning unit.


Use a pre-filter to keep squirrel cages clean.


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