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

Let’s go over 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 problems involve:

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

1. The Furnace Can’t Start

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

  • Is your thermostat set correctly? Make sure it’s on “heat,” “auto” and that your preferred temperature is greater 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 operate if it doesn’t have power. 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 close to it. Because this switch looks like a light switch, it’s easy to unintentionally turn it off. If it was off, it might take your furnace a few minutes to turn on.
  • Is the air filter clean? A dusty air filter can cause a lot of issues for your furnace. Get a new one if you can’t see light through it.

Estimated Repair Cost

This issue can be complex, so the estimated cost to repair it varies according to what’s wrong.

2. The Furnace Won’t Stay Lit

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

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

If something is wrong 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 spilling into your home. The ignition process corrodes flame sensors over time. While cleaning during annual furnace maintenance can help, yours may eventually need to be taken out and changed.
  • Bad limit switch. This safety feature will turn off your furnace if it detects backdrafting. Backdrafting is hazardous, since carbon monoxide and natural gas can leak into your home. These switches can malfunction due to age, damage or dust accumulation.
  • Old thermostat. If your thermostat isn’t working correctly, 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 avoid 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 Blows Cold Air

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

4. The Furnace Can’t Shut Down

If it’s very chilly outside or you like your home to be warm, your furnace may be running for a long time.

If this isn’t the case, ensure your thermostat is set correctly and running properly. If your fan setting is at “on,” the blower motor will be going 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, forcing your furnace to run constantly to make up for the lost air.

Estimated Repair Cost

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

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

Fire & Ice HVAC Will Work Hard to Resolve Your Furnace Issues Quickly and Affordably

Furnace issues can be a costly headache, but not when you work with Fire & Ice HVAC. We’ve been providing the quality, affordable furnace repair Manassas homeowners have trusted since {year}. Call us at 703-595-4157 to receive your free estimate today.