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Average Repair Costs for 4 Common Furnace Problems

November 30, 2021

Your furnace is an integral 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 typical than others.

Let’s go over 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 problems include:

  • 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 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 higher than the room’s current temperature. If you have 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 found on or near it. Since this switch resembles 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 create 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. Furnace Won’t Stay Lit

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

  1. Your thermostat detects the temperature has dropped and tells your furnace to start running.
  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 tells your furnace the burners have been ignited.

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

A couple of potential causes for this issue include:

  • Dirty or malfunctioning flame sensor. If the sensor doesn’t sense a flame, it will turn off your furnace to prevent natural gas from spilling into your home. The ignition process corrodes flame sensors as time passes. 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 hazardous, since 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 run.
  • Dirty air filter. A dirty air filter can reduce 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 important to note yours may vary 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 cases, this problem is tied to an incorrect thermostat setting or a dusty air filter that’s limiting airflow. Use the steps above to resolve the problem.

4. Furnace Won’t Turn Off

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, make sure 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 sound 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 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 house size

Contra Costa Heating & AC Can Solve Your Furnace Issues Quickly and Affordably

Furnace issues can be a costly headache, but not when you work with Contra Costa Heating & AC. We’ve been providing the quality, affordable furnace repair the Bay Area homeowners have trusted since 1970. Contact us at 510-343-9841 to receive your free estimate today.