Furnace Won’t Start? 7 Quick Checks

Nothing interrupts a peaceful winter evening faster than a furnace that refuses to turn on. You may feel frustrated and uncertain about what to do. Don’t panic! When your furnace won’t start, here are seven quick checks you can perform to find the issue and restore heat. If these HVAC troubleshooting tips don’t resolve the problem, then you can call in the professionals. You can depend on F.H. Furr furnace services for timely heating repair in Northern Virginia.

1. Check the Thermostat Settings

Sometimes, the easiest solution is the one that works. Make sure your thermostat is set to heat. Early in the season, it’s not uncommon for a household member to switch to cooling on a warm autumn afternoon. Also, check that the temperature you are trying to reach is higher than the existing room temperature. Double-check that the thermostat has fresh batteries if it is battery-operated. Incorrect settings or old thermostat batteries can make it seem like your furnace is not working, even when the system itself is fine.

2. Inspect the Circuit Breaker

Your furnace requires power to operate. If your furnace won’t start, check your electrical panel for tripped breakers. If the furnace breaker has flipped, switch it off and then back on to reset it. A tripped breaker could be a sign of a temporary electrical surge. However, if it keeps tripping, it may indicate a larger electrical issue that requires professional attention. This step makes sure that your furnace has the power it needs to start.

3. Look at the Furnace Switch

Many furnaces have a dedicated on/off switch near the unit, usually resembling a standard light switch. Make sure the switch is in the “on” position. It’s easy to leave it off after maintenance or other household tasks. Confirming that the furnace switch is on ensures you have not overlooked this simple but critical control.

4. Replace the Air Filter

A clogged air filter can restrict airflow and prevent your furnace from operating safely. If you have not replaced the filter in the past three months, it could be clogged. This simple step can sometimes get your furnace working again and help improve overall efficiency. Regular filter changes help prevent furnace problems from escalating into larger repairs. We also recommend professional furnace maintenance every fall. Then, you might not need to know how to fix furnace problems.

5. Ensure the Gas Valve Is Open

If your furnace uses natural gas, check that the gas valve near the furnace is fully open. A closed valve prevents fuel from reaching the burners, leaving the furnace unable to ignite. Never attempt to force or adjust gas connections beyond opening or closing the main valve. If you suspect a gas leak, evacuate your home and contact our team right away.

6. Examine the Pilot Light or Ignition Sensor

Older furnaces use a pilot light, while newer models often rely on electronic ignition sensors. If the pilot light is out, follow the manufacturer’s instructions to relight it safely. For furnaces with electronic ignition, listen for the clicking sound when the system attempts to ignite. A faulty ignition sensor or pilot light can prevent the furnace from starting even though the system is otherwise operational.

7. Check for Error Codes or Flashing Lights

Many modern furnaces include diagnostic indicators such as flashing lights or digital error codes. Consult your furnace manual or a member of our team to understand what these codes mean. Identifying the error can help you determine whether it’s a minor issue, like a dirty filter, or a larger mechanical problem.

Safety First

While these seven checks can help identify common problems, avoid opening panels or attempting internal repairs on your own. Furnaces use high-voltage electricity or gas, and they have moving parts, making DIY repairs dangerous. Always prioritize your safety and know when to call the experts.

When to Call F.H. Furr

If you have gone through these HVAC troubleshooting tips and your furnace is still not working, it’s time to call in the professionals. F.H. Furr Plumbing, Heating, Air Conditioning & Electrical offers comprehensive heating services, including heating repair in Northern VA. Our technicians can identify underlying issues safely and efficiently, and can quickly restore comfort to your home. With over 30 years of service in the DMV area, we have become a trusted part of the community. Contact F.H. Furr furnace services today for guidance on how to fix furnace problems or to schedule an appointment.