By checking the furnace's power supply, thermostat, filters, pilot and gas valve, a homeowner can determine why a furnace motor blower is not turning on or functioning properly according to popular contractor Bob Villa. Either the blower needs servicing or another component of the furnace could be causing it to malfunction.
Step 1: Check the furnace for powerAn electric surge or a power outage can cause a fuse to blow or circuit breaker to trip. Ensure that power is flowing before continuing.
Step 2: Check the thermostat settings and replace the batteriesMake sure the batteries are fully charged and that the thermostat is on the "heat" setting with fan or auto. The temperature should be at least 3 degrees higher than the current room temperature.
Step 3: Check the filtersIf the filters need replacing, this could be causing the problem. Dirty filters limit airflow and can cause a blower to shut down. Replace filters once a month to prevent this problem.
Step 4: Check the furnace power switchA furnace has its own power switch that could have been accidentally turned off. If it is off, then turning it back on easily resolves the issue.
Step 5: Check the pilotIf the furnace has a pilot light that has been extinguished, then it needs igniting. Only complete this step if comfortable working with fire.
Step 6: Check the gas valveAs a last resort, make sure the furnace gas valve is on.
If these steps have been followed and the furnace motor blower is still not turning on, an HVAC repairman should be called for further assistance.