The blower wheel is a drum fan fastened onto the axle protruding from one side of the motor. The motor also has an axle on the other side with the belt pulley attached. The blower wheel turns when the motor turns and creates a strong air current.
Before inspecting the blower, unplug the dryer or shut off the power at the fuse box or breaker panel to avoid an electrical shock hazard. Turn off the gas supply to your dryer.
If the blower wheel is loose, it may not turn with the axle. The blower wheel could also be damaged or may have reduced air flow as a result of a lint build up. Inspect the blower wheel to make sure it is not loose, clogged or damaged.
Access to the motor and blower wheel may be easiest from the front or the rear depending on your model of dryer. If you are uncertain of the location of the motor, start by removing the lower front panel. It should lift up and off or it may be held in place with a few screws. If you cannot reach the motor from the front, then you will have to remove the rear access panel which is held in place by screws along the outer edges.
When reaching into the blower wheel area be careful of sharp edges on the cabinet and interior supports. Reach in to the blower wheel and give it turn; it should either be hard to turn or if it turns, the motor's axle should turn with it. Make sure the blades of the wheel are not bent or damaged and remove any lint build up.