Top 5 Furnace Problems & Solutions: 2025

3 min readUpdated Feb. 27, 2025Lyle WeischwillFurnace
furnace troubleshooting interactive photo

As we step into fall and winter in 2025, an efficiently running furnace is more crucial than ever. This piece will delve into the top 5 furnace problems and solutions homeowners may face this year, alongside practical solutions. From thermostat malfunctions to dirty filters, discover easy DIY fixes to keep your furnace running smoothly throughout the colder months.

KEY TAKEAWAYS

  • If your thermostat isn't working, try changing the batteries, dusting inside, and rebooting it before calling for professional help.
  • Check the emergency shutoff switch for the furnace if the unit is not turning on, as it may have been accidentally switched off.
  • Regularly changing the furnace filter every one to two months can prevent various problems and lower energy bills.

Having trouble with your furnace? You’re not alone. Fortunately, many problems have easy DIY fixes. The first step: Check whether your HVAC system has power. You don't want to have a service tech come to your home just to flip a switch at the breaker box. If power isn't the problem, check other possible glitches before calling for service.

Troubleshoot furnace issues with these tips from Martin Orozco, an HVAC pro at Sears Home Services. While these suggestions work for most furnaces, you should check your furnace's manual first to make sure you’re not voiding your warranty.

#1 PROBLEM: Thermostat Isn’t Working

LIKELY CULPRIT: If your heat isn’t coming on at all, try changing the batteries in the thermostat, if it has batteries. While you’re at it, give the thermostat a good dusting inside with a small paintbrush.

You can also try to reboot it. With the thermostat set to Heat, turn the temperature down to about 60Âş. Then, turn the breaker switch off for 30 seconds and turn it back on. Still nothing? Call in an expert.

#2 PROBLEM: Unit Not Turning On

LIKELY CULPRIT: Check the emergency shutoff switch for the furnace. It might be at the entrance to the furnace closet, at the top of the basement stairs, or on the furnace. It might have a red switch plate. If someone switched it off, the furnace won't work.

#3 PROBLEM: Dirty Filter

LIKELY CULPRIT: Not swapping out an old filter can cause a host of problems, not to mention driving up your energy bill. To ensure your furnace doesn’t work overtime, change your filter every one to two months. Here’s how:

  1. Buy the replacement filter that fits your furnace.
  2. Turn off your furnace.
  3. Remove the old filter and replace it with the new one.
  4. Turn the furnace back on.

#4 PROBLEM: Furnace Isn’t Igniting

LIKELY CULPRIT: Does your furnace click as though it’s about to turn on, but then go silent and never start? If you’ve checked the power, inspected the thermostat and changed the filter, the pilot light or the ignition sensor is likely the problem. To fix it, start by turning off the gas to your furnace. Then remove the front panel and find the igniter or ignition sensor, which is usually near the burners. Snap a photo of the sensor to remind you of how it's attached and then remove the ignition sensor. Rub it with steel wool to remove residue, being careful to not damage it. Then put it back exactly as you found it and replace the panel before turning the gas back on. If you have any hesitation about this project, play it safe and call in the pros.

#5 PROBLEM: Furnace Keeps Tripping the Breaker

LIKELY CULPRIT: If your furnace keeps tripping the breaker or blowing the fuse when the heat kicks in, it’s most likely an electrical issue. To keep you and your family safe, call in the pros to diagnose the cause.

Qualified Sears Home Services HVAC technicians can diagnose and rectify more complex gas furnace problems, ensuring your furnace works safely and efficiently.

Remember, a well-maintained furnace not only ensures a cozy home but also enhances the system's lifespan and efficiency. Regular maintenance and prompt troubleshooting can keep most of these issues at bay. We're committed to helping you keep your home warm and comfortable throughout 2024 and beyond.

Frequently Asked Questions

Which furnace issues arise most frequently?
Dirty filters restricting airflow, malfunctioning thermostats, pilot/ignition problems, worn blower belts, and cracked heat exchangers. Sears Home Services can address each safely.
How do I know if the thermostat is at fault?
If the fan or burner doesn’t respond when you switch settings. Sears Home Services tests wiring and calibration to confirm if a replacement or recalibration is needed.
Is a cracked heat exchanger dangerous?
Yes, it can leak carbon monoxide. Sears Home Services inspects for cracks and recommends replacing the exchanger or entire unit if severe.
Will cleaning or changing the filter solve airflow problems?
Often, yes. A dirty filter is a leading cause of reduced airflow. Sears Home Services advises monthly checks to keep furnaces running smoothly.

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Call (213) 596-2538 or schedule online now.
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Glossary Terms

A furnace is a major appliance that heats air distributed throughout a home or building via a ductwork system.

A furnace blower motor is a crucial component of a home heating system that drives the fan responsible for circulating air throughout the HVAC system and into the living spaces of the home.

A furnace condensate pump is a device installed in HVAC systems, particularly high-efficiency furnaces, to collect and automatically remove the water (condensate) produced during the heating process.

A furnace door is a crucial component of a home heating system, providing access to the interior of the furnace for maintenance, repairs, and inspections. It helps in maintaining the system's efficiency and safety.

Common Appliance Symptoms

The most common reasons your Kenmore Elite refrigerator stopped working are a locked compressor, damaged evaporator or a defective electronic control board.

The most common reasons your Maytag refrigerator stopped working are a locked compressor, damaged evaporator or a defective electronic control board.

The most common reasons your Bosch dishwasher has no heat are a defective electronic control board, clogged water valve or a broken detergent dispenser.

The most common reasons your Kenmore Elite microwave has no power are a bad thermostat, malfunctioning electronic control board or a broken switch.

The most common reasons your Kenmore refrigerator is noisy are a faulty ice maker assembly, defective electronic control board or a locked compressor.

The most common reasons your LG freezer is leaking water are a clogged drain tube, cracked water tubing or a bad evaporator.