Estimated Repair Costs for 4 Typical Furnace Issues

November 30, 2021

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

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

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

1. Furnace Won’t Turn On

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 desired 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 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 located 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 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. Replace yours if you can’t see light through it.

Estimated Repair Cost

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

2. Furnace Won’t Stay Lit

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

  1. Your thermostat notices 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 unlocks 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 safety precaution.

A couple of possible 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 eventually need to be taken out and changed.
  • Bad limit switch. This safety feature will shut off your furnace if it detects backdrafting. Backdrafting is hazardous, since carbon monoxide and natural gas can leak 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 limit airflow and force your furnace to shut off 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 important 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. Furnace Won’t Blow Hot Air

In many instances, this problem is linked to a wrong thermostat setting or a dirty air filter that’s restricting airflow. Follow the steps above to fix the problem.

4. Furnace Won’t Turn Off

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

If this isn’t what's happening, 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.

Otherwise, there might be a problem with the blower motor or your ductwork may be leaking air, forcing your furnace to run continuously to make up for the air loss.

Estimated Repair Cost

These costs are estimates, so it’s important 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

AC Sales Can Solve Your Furnace Issues Quickly and Affordably

Furnace problems can be an expensive headache, but not when you call AC Sales. We’ve been delivering the quality, affordable furnace repair Lafayette homeowners have trusted since . Contact us at (337) 234-2345 to receive your free estimate today.