Air Comfort Services

(423) 677-7856

Troubleshooting Your Furnace

How to Fix a Furnace That Won’t Turn On

Troubleshooting Tips for Staying Warm in the Tri-Cities

Few things are more frustrating during a cold East Tennessee winter than a furnace that won’t turn on. If your home feels as chilly as the outdoors in Johnson City, Kingsport, or Bristol, don’t panic! While some issues require professional attention, there are a few things you can check before calling in the experts at Air Comfort Services.

Let’s walk you through some troubleshooting steps to get your furnace up and running.

thermostat set to heat 70 degrees

1. Check the Thermostat

The simplest problems often have the simplest solutions. Start here:

  • Ensure the thermostat is on “HEAT.” It’s easy to accidentally leave it in “COOL” or “OFF” mode.
  • Adjust the temperature setting. Raise the temperature a few degrees above the current room temperature.
  • Check the batteries. If your thermostat runs on batteries, dead batteries can cause it to malfunction.
  • Verify the display. If the screen is blank, your thermostat may need replacement or repair.

? Pro Tip: If you have a programmable thermostat, ensure the schedule settings are correct for heating.

2. Check the Power Source

Furnaces need power to operate, even if they’re gas-powered.

  • Inspect the circuit breaker. Go to your electrical panel and check for a tripped breaker. If it’s tripped, reset it by flipping the switch to “OFF” and then back to “ON.”
  • Look for the furnace switch. There’s often a switch near the furnace (it may look like a light switch) that can accidentally get turned off.

? Safety First: If the breaker trips again, don’t keep resetting it. This could indicate an electrical issue—call a professional.

3. Check the Furnace Filter

A clogged or dirty air filter can restrict airflow, causing your furnace to shut down as a safety measure.

  • Inspect your air filter. If it’s dirty or covered in dust, replace it with a clean filter.
  • Make it a habit: Replace your filter every 1-3 months during the winter season.

? Why it matters: A clean filter improves airflow, efficiency, and the overall health of your HVAC system.

dirty furnace filter

4. Inspect the Pilot Light (for Older Furnaces)

If you have an older gas furnace, a pilot light that’s out will prevent the furnace from working.

  • Look for the pilot light. It’s usually located near the bottom of the furnace.
  • Relight it if needed. Follow the instructions on your furnace or in the owner’s manual.

?? Important: If you smell gas, DO NOT relight the pilot light. Leave your home immediately and call your gas company.

5. Check the Furnace Safety Switch

Most furnaces have a safety switch on the access panel that prevents the furnace from running when the panel is removed.

  • Make sure the panel is securely closed. If it’s loose or not in place, the furnace won’t operate.

6. Look for a Fault Code

Modern furnaces have a small LED light that flashes error codes to indicate issues.

  • Find the light: It’s usually on the control board inside the furnace panel.
  • Check the code: Refer to your owner’s manual to interpret the flashes.

If you can’t resolve the issue based on the fault code, it’s time to call an HVAC professional.

7. Check the Gas Supply

If your furnace uses natural gas or propane, ensure the gas valve is open and the supply isn’t interrupted.

  • Verify the gas valve: It should be in the “ON” position.
  • Inspect other gas appliances: If they’re also not working, the issue may be with the gas supply.

When to Call the Professionals

If you’ve checked everything and your furnace still won’t turn on, it’s time to bring in the experts at Air Comfort Services. Furnace problems can stem from:

  • A faulty igniter or flame sensor.
  • Blower motor issues.
  • A malfunctioning limit switch or control board.

Attempting DIY repairs on these components can be risky and may cause further damage. Leave it to the pros!

Trust Air Comfort Services to Keep You Warm

At Air Comfort Services, we’ve been keeping homes in Johnson City, Kingsport, Bristol, and surrounding areas warm and cozy for over 20 years. Whether it’s a simple repair, a furnace tune-up, or a complete system replacement, our experienced technicians are ready to help.

?? What We Offer:

  • 24/7 Emergency Furnace Repairs
  • Reliable Service from Certified Technicians
  • Affordable Maintenance Plans

Don’t wait until the cold becomes unbearable!
If your furnace won’t turn on, call us today at (423) 677-7856 or schedule an appointment online.

? Proudly serving the Tri-Cities, including Johnson City, Kingsport, Bristol, Elizabethton, and beyond.

Stay warm, stay safe—let Air Comfort Services handle the rest!