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

Let’s review these issues and discuss what they might cost to correct 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 Will Not Turn On

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

  • Is your thermostat set correctly? Make sure it’s on “heat,” “auto” and that your desired temperature is greater than the room’s current temperature. If you have a programmable thermostat, make sure it has fresh batteries.
  • Is the circuit breaker tripped? Your furnace can’t run 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 found on or near it. Since this switch looks like a light switch, it’s easy to unintentionally turn it off. If it was off, it may take your furnace a few minutes to start.
  • Is the air filter clean? A dusty air filter can cause a lot of issues for your furnace. Replace yours 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 Ignition System Isn’t Working

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

  1. Your thermostat notices the temperature has dropped and tells your furnace to start running.
  2. The draft inducer fan activates to bring in fresh air for combustion.
  3. The gas valve unlocks for the burners, which are ignited electronically.
  4. The flame sensor signals to your furnace the burners have been lit.

If something is off during the sequence, your furnace will shut down as a safety precaution.

A couple of potential causes for this problem include:

  • Dirty or malfunctioning flame sensor. If the sensor doesn’t sense 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 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 hazardous, since carbon monoxide and natural gas can leak into your home. These switches can malfunction 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 cause your furnace to shut off to prevent overheating. Make sure to replace 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. The Furnace Is Blowing Cold Air

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

4. My Furnace Isn’t Shutting Off

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

If this isn’t what’s happening, 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.

Otherwise, there might be an issue with the blower motor or your ductwork may be leaking air, making your furnace run continuously 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 square footage

Herman Allen Plumbing, Heating & Cooling Will Work Hard to Resolve Your Furnace Issues Quickly and Affordably

Furnace issues can be an expensive headache, but not when you call Herman Allen Plumbing, Heating & Cooling. We’ve been delivering the quality, affordable furnace repair Greater Richmond homeowners have trusted since {year}. Call us at 804-302-6657 to receive your free estimate today.