Has your furnace stopped putting out heat? You may be able to troubleshoot the issue yourself and avoid having to replace your furnace. Try performing the simple tasks below to repair your furnace in just minutes.
Examine the thermostat
The thermostat is the best place to begin. Follow each of these steps in the order listed until you reach the one that works:
- Confirm the thermostat is turned on and switched to the “Heat” setting.
- Adjust the temperature to at least 5° higher than the current room temperature and listen for the furnace to start.
- Check that thermostat programming is operational and properly set:
- Make sure displayed date and time are correct
- Replace the battery and then confirm the thermostat hasn’t reverted to a default program
- Bypass program settings to see if the furnace can function manually
Replace the filter
A blower that runs without heat likely indicates the filters are too dirty for enough air to pass through, which causes the heat exchanger to switch off prematurely. Most furnace manufacturers recommend you install new air filters every 1-3 months, especially during the coldest half of the year. Consult the owner’s manual to locate the filter, the filter’s dimensions, and how to replace it.
Check for power
Power to the furnace can be controlled through either a shutoff switch or a circuit breaker. A switch is typically located right on the furnace or on a nearby wall. Flip the switch to determine if power returns to the furnace.
Next, inspect the circuit in the breaker panel that controls the furnace. If the switch has been thrown off, flip it back to the “On” position, which should align it with all other switches in the panel.
Check for gas
Locate the gas valve closest to the furnace and be certain it’s turned on, even if it’s unlikely someone would have turned it off. If you have another gas appliance, test that it works so you can rule out the possibility there’s a problem with the house’s main gas line.
If your furnace is an older model, check that the pilot light is still lit. Newer models feature a light that conveys the furnace’s mechanical status through a code of sequential flashes. Make note of the displayed code and refer to the furnace’s access panel for a key that explains the code’s meaning and recommends solutions.
Try fixing your furnace with a do-it-yourself approach. Often you can fix the problem for free, or for no more than the cost of a new air filter. Just be sure to consult your owner’s manual first. However, if you’re still unable to fire up your furnace, you may have a larger problem on your hands that requires attention from an HVAC professional. Please contact a Sears heating and cooling technician for further assistance.