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 issues that are more typical than others.

Let’s review these issues 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 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 couple of 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 set to “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 fresh 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 found on or near it. Since 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 start.
  • Is the air filter clean? A dusty air filter can cause a lot of problems 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 depends on what’s wrong.

2. The Furnace Won’t Stay Lit

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

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

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

A couple of possible causes for this issue include:

  • Dirty or malfunctioning flame sensor. If the sensor doesn’t sense a flame, it will shut 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 eventually need to be replaced.
  • Bad limit switch. This safety feature will shut off your furnace if it detects backdrafting. Backdrafting is dangerous, because carbon monoxide and natural gas can leak into your home. These switches can fail due to age, damage or dust accumulation.
  • Old thermostat. If your thermostat isn’t working properly, your furnace won’t be able to operate.
  • Dirty air filter. A dirty air filter can reduce 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 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. My Furnace Blows Cold Air

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

4. My Furnace Can’t Shut Down

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, make sure your thermostat is set correctly and running 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 on 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 lost air.

Estimated Repair Cost

These costs are estimates, 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

Pliescott HVAC Services LLC Will Work Hard to Resolve Your Furnace Problems as Soon as Possible

Furnace problems can be a costly headache, but not when you call Pliescott HVAC Services LLC. We’ve been delivering the quality, affordable furnace repair Cambridge homeowners have trusted since {year}. Contact us at 410-228-4822 to receive your free estimate today.