Furnace Not Working? This Could Be Why…
When your furnace unexpectedly goes out, try these furnace troubleshooting tips before reaching for the phone. You may be able to restore the system yourself, eliminating the discomfort that an increasingly chilly home causes.
- The thermostat. Verify that the thermostat is set to heat and the temperature setting is above the air temperature by a few degrees. If in doubt, set the thermostat four degrees higher than the room’s air. Replace the batteries if it’s not hard-wired.
- No power. All gas furnaces have a switch located in the front of the blower compartment. Reset it by pushing it or moving it to its “on” position. If it doesn’t start soon, check the circuit breaker. If the breaker tripped, reset it. If the circuit breaker trips soon after resetting it, call your HVAC contractor for professional help.
- Dirty air filter. Almost all gas furnaces have safety switches inside them that turn the furnace off when there isn’t enough air flowing through them. When furnace troubleshooting, look at the air filter. If it’s covered with dust, it won’t allow enough air into the blower compartment and if it continues to run, the components would build too much heat, creating a safety hazard. During the winter when the furnace runs routinely, it’s a good idea to check the air filter monthly and change it when it’s dirty.
- Blocked flue. If the flue vent is blocked, the furnace will automatically shut off. If you can’t access it easily, call your HVAC contractor.
- Ignition problems. Diagnosing ignition problems is fairly easy with a furnace that uses a standing pilot light. If the pilot goes out periodically, clean the thermocouple and the pilot. If the pilot still goes out, the thermocouple may need replacing. If your furnace has electronic ignition, it uses a furnace ignitor. This part uses a filament that creates a spark to ignite the fuel. They can and do wear out and should be replaced by an HVAC professional.