12.10.13It’s news none of us wants to hear, with night-time temperatures in the Valley of the Sun about to descend into the mid-40s for at least three months: nasty noises or nothing at all from our furnace. Nonetheless, it happens to some homeowners every year. If your furnace has quit on you, though, you can try some simple furnace troubleshooting before calling in professional help. Power Supply

Most furnaces are hardwired, meaning their power supply is plumbed directly into a circuit; it’s not uncommon for this circuit to be dedicated solely to the furnace, or to the HVAC system as a whole. Check that the fuse or circuit breaker that protects this part of the installation hasn’t burned out or been switched to off. If your furnace cord ends in a plug at a socket, ensure the plug is all the way in. You can also pull the plug out, then use a hair dryer or small lamp to check if the outlet is live.

Fuel Supply

The vast majority of domestic furnaces are fueled by gas, either natural or propane. If the former, make sure the on/off inline tap is turned to “on.” If your furnace is the only appliance that burns natural gas, it may be that the main control lever near the meter has been turned to “off.” If you use propane or heating oil, ensure there’s actually fuel in the tank. In either case, most older-style furnaces require a functioning pilot light to ignite the main burner(s); is your pilot flame visible and burning strongly?


The furnace won’t ignite if it’s not instructed to do so by the thermostat. Ensure the temperature is set to demand the furnace to heat your living space. A severely blocked air filter can also prevent ignition in some furnaces; a failsafe correctly interprets excessive backpressure as a blockage that could be a safety hazard.

Should you try all of these furnace troubleshooting tips to no effect, or feel the least bit uncomfortable attempting any of them, please contact Wolff Mechanical, your HVAC experts for Phoenix, Scottsdale and Central Arizona. Expert emergency help is on hand 24/7.

Our goal is to help educate our customers in the Phoenix Valley area of Arizona about energy and home comfort issues (specific to HVAC systems). 

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