A furnace that won’t heat in the middle of winter is stressful — but the cause is often something simple. Here’s what to check yourself, what the common culprits are, and when it’s time to get a professional out fast.
Call (888) 616-5525Start with the basics: confirm the thermostat is set to Heat and a few degrees above room temperature, and replace its batteries if it’s blank. Check that the furnace’s power switch (it looks like a regular light switch nearby) is on, and that the breaker hasn’t tripped. Then check the air filter — a badly clogged filter can overheat the furnace and trip its safety shutoff.
For gas furnaces, make sure the gas is on. If you have an older unit with a pilot light, check whether it’s lit (most modern furnaces use electronic ignition instead).
The usual suspects: a clogged filter causing overheating shutoffs; a faulty igniter or flame sensor so it won’t fire or won’t stay lit; a bad thermostat; a tripped high-limit switch; or a blower motor problem. Short-cycling — firing up then shutting off repeatedly — is most often a clogged filter or an overheating limit switch.
If the furnace runs but blows cool air, or the fan never stops, those point to ignition or control issues a technician should diagnose.
Some symptoms aren’t DIY territory. If you smell gas, leave the house and call your gas company and a professional immediately. A cracked heat exchanger can leak carbon monoxide, so a working CO detector is essential, and any soot, a persistent yellow burner flame, or unusual odors warrant an urgent service call.
For a true no-heat emergency, Ventroute connects you with an available local heating contractor 24/7 — just call (888) 616-5525.
That’s short-cycling. The most common causes are a clogged filter or an overheating limit switch, followed by a dirty flame sensor. A tech can pinpoint it quickly.
You can safely check the thermostat, power switch, breaker, gas valve, and filter. Anything involving the igniter, flame sensor, gas components, or electrical parts should be handled by a licensed pro.
We connect you with an independent, licensed contractor in your area — 24/7.
Call (888) 616-5525