When winter hits, the last thing you want is a furnace that will not start. While some heating issues require professional attention, there are a few simple things homeowners can check before calling an HVAC technician. Identifying the cause early can save you time, money, and stress. North Country Aire will share the top things to check if your furnace will not start.

Check the Thermostat

Your thermostat controls when your furnace turns on, so it is the first place to start. Make sure it is set to “heat” and the temperature is higher than the current room temperature. Replace dead or weak batteries and confirm the thermostat is functioning correctly. Some units may need recalibration.

Inspect the Circuit Breaker

A tripped breaker or blown fuse is a common reason a furnace will not start. Locate your home’s electrical panel and check for tripped switches or blown fuses. Reset the breaker or replace the fuse safely. If it trips repeatedly, this could indicate a serious electrical problem so call a professional.

Examine the Pilot Light or Ignition System

Gas furnaces rely on a pilot light or electronic ignition to start. If your pilot light is out, follow the manufacturer’s instructions to relight it. For electronic ignition systems, a faulty igniter or flame sensor may be the cause. If relighting doesn’t work, call an HVAC technician to inspect the ignition system.

Check the Air Filter

A clogged air filter can restrict airflow and prevent the furnace from starting. Remove the filter and inspect it for dirt or debris. Make sure to replace if necessary typically every 1 to 3 months. A clean filter helps your furnace run efficiently and prevents overheating.

Inspect the Gas Supply

If your furnace runs on gas make sure the gas valve is open. Check that your propane tank is not empty if applicable. Be alert for any gas smell. If you detect gas, evacuate your home immediately and call your gas company.

Look at the Safety Switches

Furnaces have built-in safety switches to prevent damage or hazards.
• Limit switches prevent overheating
• Pressure switches monitor airflow
• Flame rollout switches detect flame problems
If one of these switches is tripped or faulty, your furnace may not start. These issues require professional attention.

Examine Vents & Airflow

Blocked vents or intake/exhaust pipes can prevent proper furnace operation. Check for obstructions like snow, ice, or debris around exterior vents. Ensure indoor vents are open and unblocked. Good airflow is critical for both performance and safety.

When to Call a Professional HVAC Contractor

If you have gone through this checklist and your furnace still will not start, it is time to contact a licensed HVAC technician. Issues like faulty blower motors, ignition failures, electrical malfunctions and gas leaks, require professional diagnostics and repair.

Central Boiler & Furnace Heating Inspection, Troubleshooting, Diagnosis, Repair, Tune Up Maintenance & More in Mora, Cambridge, St. Francis, Oak Grove, North Branch & Greater Isanti, Minnesota

A furnace that will not start can be stressful, but a few quick checks can often help identify simple issues. For problems that go beyond basic troubleshooting, a professional service is the safest and most reliable option. For help repairing your furnace, contact North Country Aire and schedule our services today.