Troubleshooting Common Furnace Problems

December 14, 2021

This can happen to the best of us: You wake up on a frigid Minnesota morning only to realize you can see your breath while standing in the kitchen. The furnace isn’t working. So now what? A properly functioning furnace is one of the most important long-term investments you can make in your home. Whether you have a conventional gas furnace or a high-efficiency condensing unit, understanding the basics of how the heating system works is crucial for any homeowner. Before you make that panicked call to your local technician, let’s look at some common furnace problems and how to troubleshoot them.

Won’t Turn On

Check to see that the thermostat is set to heat and that it’s at least five degrees above the room’s temperature. For electrical/programmable models, make sure the date and time are correct as the system may be on a timer. If your home’s thermostat runs on batteries, perhaps it’s time to replace them. You should replace the batteries on your thermostat at least once a year.

Doesn’t Produce Enough Heat

Check the filter. Is it dirty or clogged? The air filter should be clean and in good condition to ensure the furnace produces enough heat. Next, try moving the thermostat dial up or down to see if that makes a difference. If not, look for a tripped/blown circuit breaker or fuse. To test for a tripped/blown breaker:

• Find the electrical panel in your home; this is usually located in the basement.
• Look for the circuit that controls the furnace.
• Manually test the breaker by flipping it back and forth between on and off.
• If the breaker is in the off position, turn it to on.

Furnace Isn’t Blowing Air

Look at the inspection window located on the unit to ensure the blower is clear of debris. There should be a flashing green or red light. If you experience an issue, check the flashing code against the owner’s manual to determine what kind of problem the system is reporting. Then, reach out to a professional for heating repair service.

Pilot Light is Out

Does your furnace operate with a pilot light? Most systems today have an electronic ignition. But if you do have a pilot light, drafts or clogs in the furnace could cause it to go out. Before you rekindle the pilot light, make sure to turn off the gas for at least 15 minutes. Your furnace flame should be constant and bluish in color. A flickering or yellow light in a gas furnace may be an indication of excess carbon monoxide. If this happens, call your technician immediately.

Blower is Always Running

If the blower won’t shut off, there are many reasons as to why. Let’s say the system isn’t heating and you don’t want the fan to continually run. Check to see that the fan switch on the thermostat is set to auto and not on. Next, check the limit switch. Is it closed? When the limit switch trips, the pilot light/heating element shuts off. This causes the blower to continuously run to clear the heat from the unit. The blower will run until the system is reset and the limit switch closes. If the limit switch is open, you will need to call your heating technician to assess and diagnose the reason and replace the switch if needed.

These are just a few common furnace problems and what you can do to troubleshoot them. The best way to keep your system in proper working condition and prevent costly repairs down the road is to have it inspected annually by a heating professional. Hanson’s Plumbing and Heating is family-owned and operated, offering repair, maintenance, and 24/7 emergency HVAC services throughout central Minnesota. Keep your home warm and comfortable this winter. Contact us today to schedule your annual furnace tune-up.