Your heat may not be kicking on due to issues like a tripped breaker, thermostat malfunction, dirty air filter, pilot light or ignition failure, or gas supply problems. It could also be caused by a clogged vent or overheating, triggering a safety shutoff.
While there are several reasons your heat pump or furnace might not be working, these are the most common ones:
If your thermostat says “heat on” but no warm air is coming through, the issue may be as simple as dead batteries, incorrect settings, or a clogged filter—or as serious as wiring or equipment failure.
Tripped Circuit Breaker
Most heating systems are connected to the electrical panel. If there's been a power surge or other electrical issue, the breaker controlling your heating system might have tripped. Resetting the breaker may solve the problem, but if it continues to trip, it's best to call a professional.
The most common furnace fuse blown signs are:
Resetting can recalibrate the temperature sensor. Failure to Turn On HVAC System: A thermostat reset reboots its system and attempts to restart normal functioning. This resolves problems where it fails to turn on your AC, heat, or fan.
Inspect the Circuit Breaker: Go to your home's electrical panel and check if the furnace's breaker has tripped. If it has, flip it completely off and then back on to reset it. Check the Furnace Power Switch: Look for a power switch on or near the furnace unit itself and make sure it is in the "on" position.
Locating the Reset Button
To find it, you should first turn off your HVAC system to ensure safety. Remove the thermostat cover by either snapping it off or unscrewing it, depending on the model. Most modern thermostats will have a clearly marked reset button inside the panel.
How can you tell if a thermostat is bad?
The most common reasons include thermostat issues, dirty air filters, and ignition failures. An improperly set thermostat can stop the heating cycle from starting, while a clogged filter may cause overheating that shuts down the burners.
How Long Can My House Stay Warm Without Heat? Most homes begin losing heat within a few hours, and depending on outside temperatures, can drop to unsafe levels within 12 to 24 hours.
What to do if your central heating stops working
Most modern furnaces come with a built-in safety reset button that will trigger when the furnace is not safe to run. It's a red or yellow button inside the furnace either near the burners or somewhere inside the blower compartment.
You may feel this is the easiest and most harmless step, but the reset method is not the same for all types of systems, and it is not right to reset your system frequently. If you face the same problem more than once or twice, do not reset your system every time. It will damage your furnace.
To diagnose a furnace issue, start by checking the thermostat settings and ensuring it's set to "heat" and at the right temperature. Inspect the air filter for clogs and replace if dirty. Ensure the furnace switch and circuit breaker are on.
A frozen pipes furnace failure can cause major problems inside your home. Ice builds up fast in unheated spaces, and when frozen water expands, it can burst pipes wide open. That kind of mess is the last thing anyone wants during a winter heating outage.
Typically, a furnace should cycle 3 to 8 times per hour, running for about 10 to 15 minutes each time. If it's cycling more frequently (short cycling) or running for 20+ minutes straight regularly, something's not right.
Table of contents
Capacitors are used in nearly every heating system, from gas furnaces to electric furnaces to heat pumps. Even though other parts can fail, like the ignitor in a gas furnace or the compressor in a heat pump, the capacitor is by far the most common part to fail on a furnace because almost every system relies on one.
The heat exchanger is often considered the most costly part of a furnace to repair or replace. It is a critical component that transfers heat from the combustion process to the air that circulates throughout your home. Over time, heat exchangers can crack due to the constant heating and cooling cycles they undergo.