The blower housing contains the fan itself, usually a cylindrical squirrel-cage type, a motor to drive the fan, a belt between the motor and fan, and the air filter. Vacuum out the entire fan compartment and check the tension of the drive belt. If pressed with a finger, the belt should deflect no more than about one-half inch. If the belt is loose, adjust the tension by loosening the motor-mounting bolts slightly, pulling the motor away from the fan to tighten the belt, and retightening the bolts. Again, if in doubt about how to tighten the belt, watch a technician do it.
Many older blowers have motors and fans that require lubrication.
The lubricating holes or cups are at the bearing ends of the fan and motor, and are often covered by small caps or plugs. If no lubricating points can be found, the bearings are probably permanently lubricated. Owners of gas heaters should perform an important safety check at the start of each heating season. This tests the venting, or draft, of the heater, which is important to make sure combustion products such as carbon monoxide are being properly vented to the outside. To check the draft, turn up the thermostat to start the heater, and let it run for about 10 minutes.