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Furnace Not Turning on? Here’s What It May Mean

With parts of the country already enjoying the first snowfall, it’s time to gear up for the home heating season. If you’re considering turning on your heater for the first time since last winter, you’ll want to read today’s post.

When things go smoothly, you switch over from COOL to HEAT, and the warm air circulates. Everybody hits a rough patch at some point, and yours might be today. What do you do when you realize it’s cold outside, and you’re dealing with a furnace not turning on?

Take a minute and explore the many reasons why people turn on the furnace and hear, well, nothing but crickets. We’ll start with the most logical and easiest to fix and then move on to a few more complex issues that may require home furnace repair.

Check Your Electrical Panel

Before you do anything else, make sure you have electricity going to the furnace. Even if your system runs on natural gas or oil, it needs electricity to run the mechanical components.

Open the electrical panel and look for a tripped breaker. If resetting the breaker works, you’re back in business. If you turn the furnace on and it trips a circuit again, you have a different type of issue to solve.

Possible reasons a furnace continues to trip circuits include:

  • Short Circuit
  • Ground Fault
  • Overloaded Shared Circuit
  • Overloaded Furnace

You may also have a general problem with the electrical panel or your circuit breakers.

Please don’t continue resetting a tripped breaker. To avoid starting a fire, contact your HVAC professional to come out and troubleshoot.

Have You Met Your Blower Compartment?

The next issue you should for when the furnace doesn’t turn on is the filter. For first time homeowners and people who haven’t changed the filter since they moved into the house, you’ll need to figure out where the manufacturer decided to place it.

In most heating systems, you’ll find the filter in the blower compartment.

It’s better if you know where to find and how to change your furnace filter before things go awry. A dirty filter can cause a heating system to shut-down.

To understand why you’ll need to grasp the role the filter plays in keeping your furnace running. Filters trap dust and debris, including pet hair.

If you or the previous homeowner ran the furnace last winter (or for several winters) without changing the filter, it’s likely clogged with grime and dust. The result is restricted airflow, the heat exchanger’s potential to overheat, and, eventually, limit switch failure.

What Is a Limit Switch?

Now, we’re getting down to the nitty-gritty—on its own, a dirty filter may not interfere with your furnace turning on, but if it causes overheating in the heat exchanger too many times, it could kill the electronic limit switch.

Every furnace has one, and the limit switch plays two roles. One is to tell the blower fan when to turn on and off. The other function, and the one we’re concerned about here, is to act as a safeguard.

If the heat exchanger overheats due to airflow restriction (caused by that dirty filter), where does the heat go? It can’t move out of the furnace, which creates a safety hazard.

On a forced-air furnace, the limit switch, when it works correctly, shuts off the gas supply to the furnace burners.

If your furnace is not turning on, you may have a faulty limit switch. Also, if the limit switch forces shut-off of the furnace burners too often, the furnace could go into a hard shut-down. At that point, your heater repair technician will need to service the furnace.

Set the Thermostat on HEAT

You might chuckle a bit, but before you start rolling on the floor, check your thermostat! All HVAC technicians have at least one humorous story to tell about service calls for broken furnaces.

When the furnace won’t turn on, and you know you’ve changed the filter, your thermostat could be the problem. Make sure you’re not still using the COOL setting. Furnaces don’t work unless you set the thermostat to HEAT.

Once you verify you’re using the right command, make sure you’ve set the thermostat to the right temperature. If the room temperature is warmer than the temperature you set for the furnace to turn on, you’ll need to bump the thermostat up.

Remember, we’re not laughing at you. We’re laughing with you (and at ourselves, too).

Here’s one more thing to think about when it comes to thermostats. If you haven’t updated yours in a few years, why not consider installing one of the new, programmable thermostats

Faulty Ingitors Ruin a Cozy Night

Finally, let’s talk about another common culprit. If you’ve investigated the issues we’ve covered and none of them seem to be the cause of your furnace not turning on, you could have a problem with the ignitor.

Newer gas heaters use an electric ignitor, which lights the furnace. The process goes like this:

  • Ignitor Sparks
  • Burner Lights
  • Gas Valve Opens

All of the above initiate combustion, which you need to create heat. A faulty ignitor makes it nearly impossible for a furnace to turn on.

While the ignitor could be dirty, it may also need replacement. If you’re intent on spending a cozy evening at home, schedule an appointment with a qualified home furnace repair company. By the way, inspecting and cleaning the ignitor is typically something your HVAC technician does as part of your annual furnace maintenance.

Is Your Furnace Not Turning On?

We’ve shared some of the most common problems that cause a furnace to give you trouble. What we haven’t talked about are things like broken blower motors or heating elements on electric furnaces.

Start your troubleshooting with the issues most straightforward to identify. Then, let your heating and cooling professional give your furnace a more thorough inspection.

There’s nothing as disheartening as a furnace, not turning on when you need warmth. The team at Jerry’s Heating and Cooling understands how vital a working furnace is when the temperature drops. Known as one of the favorite heating companies in the area, we’d love to welcome you into our family.

Contact us today to schedule service!

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