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Why won’t my furnace turn on?


As we move closer towards the winter months, there are certain things we can count on: the ground to be less green, the inevitable snowfall, and our homes to be warm and cozy. Many of us have already switched on the heat on our furnaces and become accustomed to the warm air being pushed around our houses. But, what if one day your furnace suddenly didn’t turn on? What if that guarantee of a cozy home waiting for you after work wasn’t a guarantee today?

Don’t panic! There are many reasons your furnace could be failing to turn on. You most likely need to contact an HVAC professional to solve the issue, but it’s still nice to try to go into the conversation with the technician with as much information as you can. And, sometimes, the issue is a small one you can solve yourself. If you want to get a better idea of what could be causing your furnace to fail, zip through the list below!

Questions to ask if your furnace won’t turn on

  1. Is my thermostat on and set correctly? We aren’t trying to be funny or offensive with this question. It’s just a simple truth that the best place to start when your furnace won’t turn on is by checking the thermostat. Do you have it switched to “heat?” Sometimes, we change the temperature, but forget to switch the setting on our thermostat. If your heat is on, is the thermostat set to the correct temperature? You may have a programmable system, and sometimes these systems can go back to their default settings if they lose power even for a few seconds. If your power has flickered recently, that could be the culprit.
  2. Is my circuit breaker flipped? If you look at your thermostat, is your system on? If not, this could actually be an electric issue. Find the breaker box in your home, and locate the breaker that controls the power to your furnace. If it’s tripped, you can flip it back to see if that gets your furnace running again. The unit itself should also have its own redundant circuit breaker or “on” switch. This will be a switch on the unit, or it will be what looks like a light switch near it. Make sure this switch is on, too.
  3. Is my air filter clogged? Our air filters are a bit out of sight, so many homeowners forget to change them regularly. If one of your filters is clogged, your furnace may shut off to prevent overheating. This is a nice safety feature! Change your filter, and see if that gets your furnace going.
  4. Is my fuel supply empty? An empty gas or propane tank will certainly keep your gas furnace from running. Are you overdue for a refill?
  5. Is my pilot light out? Even some newer systems still use a pilot light, and if it goes out, your furnace may have a safety feature that keeps the furnace from turning on and pumping pure gas into your home. If you are familiar with lighting a pilot light and feel comfortable doing so, have at it. If not, call a professional. There’s no need to play with fire!
  6. Is my drain pan full? As your heating and cooling system runs, it pulls water from the air. This water accumulates in a drain pan. If your pan has a drain system, check to make sure the drain is clear. Clean the drain, get rid of the water, and see if your furnace starts running. If your furnace pan has a pump with a float switch, check to see if your switch is up or down. If it’s up, your system won’t run, so you need to clear it out, drain the water, and get it to go back down. If it’s stuck in the up position, you may need a new pump.
  7. Is my gas valve on? This last one might be a stretch, but if you have a gas furnace, you can always check to make sure the gas line coming into your home wasn’t somehow turned off.

Please note, while some of these issues can be fixed easily by you as the homeowner, you should never try anything yourself that you don’t completely understand or feel 100 perfect comfortable doing. You can always contact James A. Wheat & Sons for professional HVAC services—we’re here for you!

For furnace repairs, rely on James A. Wheat & Sons

If you go through all of the questions above, and you still can’t get your furnace to kick on, it’s time to call the professionals at James A. Wheat & Sons to come out and assess the problem. We’ll diagnose the problem and let you know if you’re in need of furnace repair. We’re a family owned and operated business, so we understand the importance of your home being comfortable and safe. Count on us to fix the problem quickly and professionally.

Call James A. Wheat & Sons today at (301) 241-9636! We’re ready to help!

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