Furnace not working? Try these checks first

When to stop and call a pro

• You smell gas or burning, or the carbon monoxide alarm sounds.
• The breaker trips again after you reset it.
• The furnace starts, then shuts off over and over, or makes banging, squealing or grinding noises.
• You see water pooling around the furnace that isn’t from a simple drain clog.
• It still won’t heat after the checks above.

Gas connections, burners and the heat exchanger are jobs for a trained technician. ENERGY STAR warns that faulty gas connections are a fire hazard and that a dirty burner or cracked heat exchanger can make equipment run less safely.

Protect your home while you wait

In a deep freeze, a house without heat can freeze pipes. Keep cabinet doors under sinks open, let a faucet on an outside wall drip, and read our frozen pipe guide. If you use a space heater, keep it away from anything that can burn and never leave it running unattended. Never use a grill, camp stove or generator indoors: CPSC says one portable generator can produce as much carbon monoxide as hundreds of cars.

How to avoid overpaying

• Ask about the service-call fee before they come. Find out what the trip charge is, whether it’s credited toward the repair, and if after-hours rates apply.
• Get the diagnosis and price in writing. Ask what failed, the part name, and the total cost before work starts. In Illinois, repair work over $1,000 needs a written contract or work order that states the total cost.
• Ask about warranties. The part may still be under the manufacturer’s warranty, especially on a newer furnace. Have the model and serial number ready.
• Second opinion on a replacement. If the first visit ends with “you need a new furnace,” it’s reasonable to get another written estimate before you sign, unless it’s a safety emergency.

Help paying for heat and repairs in Illinois

The Low Income Home Energy Assistance Program (LIHEAP) helps eligible households pay heating bills. For the 2026-27 season, older adults, people with disabilities, families with a child 5 or under and households facing disconnection can apply from October 1, 2026; all other income-eligible households can apply from November 1, 2026. Apply at helpillinoisfamilies.com or through your local agency. The Illinois Home Weatherization Assistance Program can help income-eligible households with furnace repair or replacement, and ComEd customers can check current heating and cooling discounts.

The federal energy efficient home improvement tax credit for furnaces ended for equipment installed after December 31, 2025, so don’t count on it for a 2026 replacement.