Your furnace is a key part of your home. Without one, you wouldn’t be able to stay warm during cold weather. Yet furnaces can have some problems that are more common than others.

Let’s review these problems and discuss what they might cost to fix so you know before you contact an HVAC technician. Some of the most common furnace repair issues include:

  • Furnace won’t turn on
  • Furnace doesn’t stay lit
  • Furnace won’t blow hot air
  • Furnace won’t turn off

1. My Furnace Isn’t Turning On

There are a couple of reasons why your furnace won’t turn on, so make sure to check all of them.

  • Is your thermostat set right? Make sure it’s set to “heat,” “auto” and that your preferred temperature is higher than the room’s current temperature. If you use a programmable thermostat, make sure it has new batteries.
  • Is the circuit breaker tripped? Your furnace can’t run if it doesn’t have electricity. Reset the switch if it’s facing the outside of the electrical panel.
  • Is the furnace switch off? Your furnace has a power switch located on or near it. Because this switch looks like a light switch, it’s easy to accidentally turn it off. If it was off, it might take your furnace a few minutes to turn on.
  • Is the air filter clean? A dirty air filter can create a lot of issues for your furnace. Get a new one if you can’t see light through it.

Estimated Repair Cost

This problem can be complicated, so the estimated cost to repair it depends on what’s wrong.

2. My Furnace Won’t Stay Lit

Your furnace follows a specific sequence when it begins heating your home.

  1. Your thermostat notices the temperature has fallen and tells your furnace to turn on.
  2. The draft inducer fan activates to pull in fresh air for combustion.
  3. The gas valve opens for the burners, which are lit electronically.
  4. The flame sensor tells your furnace the burners have been ignited.

If something is off during the sequence, your furnace will shut off as a preventive measure.

A couple of potential causes for this problem include:

  • Dirty or malfunctioning flame sensor. If the sensor doesn’t detect a flame, it will turn off your furnace to keep natural gas from getting into your home. The ignition process corrodes flame sensors over time. While cleaning during annual furnace maintenance can help, yours may ultimately need to be taken out and changed.
  • Bad limit switch. This safety feature will turn off your furnace if it detects backdrafting. Backdrafting is dangerous, because carbon monoxide and natural gas can seep into your home. These switches can fail due to age, damage or dust buildup.
  • Old thermostat. If your thermostat isn’t working properly, your furnace won’t be able to run.
  • Dirty air filter. A dirty air filter can restrict airflow and force your furnace to shut down to prevent overheating. Make sure to change yours every 30 to 90 days, or whenever you can’t see light through it.

Estimated Repair Cost

These costs are estimates, so it’s necessary to note yours may fluctuate based on your furnace’s brand and model.

  • Flame sensor: $350–$500
  • Limit switch: $150–$300
  • Thermostat: $150–$350
  • Furnace filter: $10-$30

3. My Furnace Is Blowing Cold Air

In many instances, this problem is tied to an incorrect thermostat setting or a dusty air filter that’s restricting airflow. Use the steps above to resolve the problem.

4. The Furnace Won’t Turn Off

If it’s extremely cold outside or you like your home to be toasty, your furnace may be running for a long time.

If this isn’t the case, ensure your thermostat is set correctly and working properly. If your fan setting is at “on,” the blower motor will be running even when the furnace isn’t, so it’ll seem like your furnace is running all the time.

Alternatively, there might be a problem with the blower motor or your ductwork may be leaking air, making your furnace run constantly to make up for the lost air.

Estimated Repair Cost

These costs are approximations, so it’s necessary to note yours may vary based on your furnace’s brand and model.

  • New blower motor: $250–$800
  • Seal ductwork: varies based on house size

B & B Heating & Cooling Can Get to the Bottom of Your Furnace Problems Quickly and Affordably

Furnace issues can be a costly headache, but not when you work with B & B Heating & Cooling. We’ve been delivering the quality, affordable furnace repair Florissant and St. Charles homeowners have relied on since {year}. Call us at 314-325-7552 to receive your free estimate today.