What to Check Before the First Cold Night
If your furnace won’t start after sitting all summer, check 6 things first: the thermostat setting and batteries, the breaker and furnace power switch, the air filter, the furnace door panel, the vents, and the condensate drain line.
If it still won’t heat, or you smell gas, hear banging, or your carbon monoxide alarm sounds, stop and call a licensed technician. If the steps below don’t restore heat, book a furnace repair visit with Dee’s.
That first chilly night in Northeast Ohio always sneaks up on us. You bump the thermostat to heat, wait a few minutes, and… nothing. Or worse, cold air. Before you panic, here’s what our technicians check first, and when it’s time to pick up the phone.
Why do furnaces act up on the first cold night?
Your furnace has been sitting idle for 4 or 5 months. Dust settles on the burners and sensors, filters get clogged from running the AC all summer, and small parts like the flame sensor or igniter can fail on their first start of the season. That burning-dust smell for the first few minutes is normal. Anything that lasts longer is not.
The 6-point check you can do yourself
- Thermostat: Set it to Heat, raise it 3 to 5 degrees above room temperature, and replace the batteries if the screen is dim or blank.
- Power: Check the breaker panel, and make sure the switch on or near the furnace (it looks like a light switch) is on.
- Air filter: Hold it up to a light. If you can’t see light through it, replace it. A clogged filter can shut the furnace off to protect itself.
- Furnace door: The front panel has a safety switch. If it isn’t seated all the way, the furnace won’t run.
- Vents and returns: Make sure furniture, rugs or summer storage aren’t blocking them.
- Condensate line (high-efficiency furnaces): If the small drain line or pump is clogged, many furnaces shut down to prevent a leak.
Is it an emergency, or can it wait until morning?
Call right away, day or night, if:
- You smell gas. Leave the house first, then call your gas utility or 911 from outside.
- Your carbon monoxide detector goes off.
- The furnace is making banging, screeching or grinding noises.
- It’s below freezing and you have infants, older family members, or someone with health concerns at home.
- You have no heat and a hard freeze is coming. Frozen pipes can follow within hours (see our tips in how to protect your pipes before the first freeze).
If the house is just a little cool and none of those apply, a next-day appointment usually works fine.
What does a technician check that I can’t?
Our licensed techs test the igniter and flame sensor, check gas pressure, inspect the heat exchanger for cracks, and test for carbon monoxide. Most first-start problems come down to a dirty flame sensor, a failed igniter or a clogged drain, which are fixable in one visit.
How can I avoid this next year?
A fall check-up catches worn parts before the first cold snap. Right now, our Early Bird Furnace Check-Up is $59 (regularly $149) through October 29. If you do need a repair, the furnace repair service fee is $89 (regularly $149) through November 1. See all current offers on our coupons page.
Still stuck? Let’s talk it through.
You don’t have to guess. Call us at (330) 554-7015 and tell us what you’re seeing, whether it’s cold air, clicking, a blinking light or nothing at all. We’ll help you decide if it’s a quick fix or a visit, and we’re available 24/7 for true emergencies.
Dee’s Heating & Cooling has been family-owned since 1978, with 70+ years of combined experience serving Wadsworth, Medina, Brunswick, Norton, Barberton, Cuyahoga Falls, Green, Uniontown and North Canton.
Frequently asked questions
Why is my furnace blowing cold air?
Usually a thermostat set to “fan on,” a dirty flame sensor, a clogged filter or a failed igniter. If a new filter and thermostat check don’t fix it, call a technician.
Is a burning smell normal when I first turn on the heat?
A dusty smell for the first 15 to 30 minutes is normal. A strong electrical or rotten-egg smell is not. Leave the house and call if you smell gas.
How much does a furnace check-up cost?
Our Early Bird Check-Up is $59 through October 29, 2026.
Related reading: Furnace blowing cold air? What it usually means · How to protect your pipes before the first freeze · Repair or replace your furnace this winter?