You can fix this
Next step: the guide that fits what you see
Your heat has power and a call for heat, or you have a heat pump, a boiler or a blank thermostat. A more specific guide will get you to the cause faster. Each one starts with checks you can do yourself and tells you when to call a pro.
Why this happens
Trane lists the thermostat, power, airflow, the gas supply and the igniter among the reasons a furnace won't heat, and Carrier says that if the fan works but there is no heat, the problem may be in the burner or ignition. Honeywell says a blank thermostat screen usually points to a power problem, such as dead batteries, a tripped breaker or a loose furnace door panel. Each of these has its own guide on this site, and so do heat pumps and boilers.
How to fix it
- The thermostat screen is blank: use the thermostat screen blank guide.
- The furnace clicks or tries to start but never lights: use the furnace clicking guide.
- The fan runs but the air from the vents is cold: use the furnace blowing cold air guide.
- You have a heat pump: use the heat pump not heating guide.
- You have radiators or baseboards: use the radiator and baseboard guide.
- Whatever you see, don't open the furnace or try to light, clean or adjust anything inside it. That is a job for an HVAC technician.
When to stop. If you smell gas or rotten eggs, leave the house without touching any switch and call 911 or your gas utility from outside. If a carbon monoxide alarm sounds, or anyone feels dizzy, sick or has a headache, get everyone outside to fresh air and call 911. If you see smoke or flames, get out and call 911. If you notice a burning plastic or electrical smell once the furnace runs, Carrier says to turn the furnace off and have a qualified HVAC professional inspect it before you use it again.
If this does not fix it, tell the HVAC technician
- What kind of heat you have and what it does when the thermostat calls for heat.
- What the thermostat shows.
- The checks you've already done: power, thermostat setting, switch and breaker.
- The brand and model of the furnace, heat pump or boiler.
Build the full list: what to tell the HVAC technician.
Start this troubleshooter over
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