Electric furnaces are excellent home heating systems that let you enjoy cozy and comfortable indoor spaces when the weather gets cold. But if your electric furnace isn’t turning on, you’ll be left with a cold home and a million questions why. If this happens, you must get to the bottom of the issue to find an appropriate solution.
Your electric furnace isn’t turning on because of a power failure, thermostat issues, a dirty filter, broken or loose wires, or defective limit control. Fix the problem by inspecting the circuit breaker and wires, checking the thermostat, replacing the filter, and replacing the limit control switch.
In this post, you’ll learn what’s the most likely cause behind your electric furnace not starting and what you should check before contacting an HVAC expert.
Power Failure
Before everything else, verify your furnace is getting electricity. A recent power outage may have caused the unit to shut down. And it simply didn’t come back on when the power was restored.
How To Fix
Press the reset button and wait to see if your electric furnace turns on.
If it doesn’t, check the circuit breaker. Your furnace has a dedicated breaker in the electrical box. If it tripped, your furnace can’t get power. Ensure the circuit breaker switch is flipped to ON.
Your furnace’s circuit breaker likely tripped because of a weak breaker, a loose wire in the breaker, or a shorted component.
If you turn the switch back on and it drops again almost immediately, you may have to replace the breaker, tighten loose wires, or replace defective furnace parts. I advise leaving this job to an expert, especially if the tripping is caused by a furnace component you aren’t familiar with.
Thermostat Issues
The thermostat controls your heating system to ensure you have heat coming through the vents when needed. It’s such a crucial part of your furnace that a small malfunction can cause the entire system not to turn on.
If your electric furnace is getting power and still won’t start, the thermostat is the next thing you should examine.
How To Fix
Check to see it’s set to HEAT. Additionally, turn the temperature a few degrees higher than the current reading and see if the system responds.
If your electric furnace still isn’t responding, check the batteries. You want to ensure they aren’t empty, as batteries on their way out could cause the device to send wrong signals to the heating elements. Replace older and dead batteries and wait to see whether the furnace will come on.
Hopefully, replacing old batteries will get your furnace to turn on. If it doesn’t, call in your HVAC guy — the thermostat could be faulty and needs replacing.
Dirty Filter
The furnace filter keeps the air entering the furnace clean by trapping dust, hair, and debris. It stops these objects from clogging the internal parts of the furnace to keep the unit working optimally.
If you haven’t cleaned or changed your filter recently, chances are that dirt has entered the furnace and is now interfering with its functioning. That’s why your furnace can’t turn on.
You see, electric furnaces come with safety features that shut down the system when they find a component that isn’t working as it should. If, for instance, some of the dirt has made its way to the blower motor or the heating elements, it will clog these components, causing them to malfunction or draw more current than they should.
To prevent damages caused by such parts, the system will automatically shut down, and every time it tries to come on, it’ll shut off again. You’ll think the furnace isn’t coming on, but in reality, it’s being turned off prematurely.
A clogged filter restricts airflow into the furnace too. As a result, the system starts to overheat, and even before it gets too hot, the limit switch shuts it off immediately to prevent damage.
How To Fix
Check to see if a dirty filter is causing your electric furnace’s startup failure. Depending on the filter type your furnace runs on, you either have to clean or replace the filter.
Reusable filters should be cleaned with running water, and disposable ones should be replaced by simply removing the dirty filter and installing a new one.
Regardless, all filters should be cleaned or replaced every 30–90 days.
Broken or Loose Wires
The inner components of your electric furnace use cables to send electric current to each other. Over time, the vibrations produced by the furnace as it runs cause these cables to snap or loosen. When this happens, your thermostat will likely not be able to communicate with the furnace’s sequencer.
A sequencer is a device positioned between the thermostat and the heating elements and controls how the elements heat air. If the cables linking the thermostat to the sequencer are broken, the thermostat will have trouble communicating with the furnace and won’t turn on.
How To Fix
Identifying the misbehaving wires can take a little bit of time. You must test each wire with an ammeter to identify the dead ones. You may want to leave this job to a professional. Nevertheless, fixing or replacing broken wires will solve the problem.
To prevent problems with broken or loose wires in the future, fix all wires into place with zip ties.
Defective Limit Control Switch
The limit switch is a built-in safety feature that keeps the furnace and your home safe when the combustion chamber gets too hot. It shuts down the furnace to prevent damage from overheating.
Over time, the switch can malfunction, especially if you have problems with weak airflow. As mentioned earlier, lack of sufficient air is one reason a furnace overheats, and every time this happens, your system shuts down. If the switch turns the furnace off repeatedly, it’ll wear out quickly and eventually stop working.
How To Fix
A faulty limit switch will turn the furnace off immediately when it tries to come on. If you’ve had repeated problems with overheating before, there’s a chance your limit control switch is broken, and that’s why your electric furnace isn’t turning on.
Fixing this problem usually requires replacing the limit switch, which is a job best left to a professional.
The Takeaway
Most electric furnace startup problems are things you can quickly address unaided or with the help of a heating expert. To get your system working again, make sure:
- The furnace is getting power.
- There is communication between the thermostat and the furnace.
- The air filter is clean.
- There are no loose wires.
- The limit control system is not shutting down the furnace prematurely.
One of the most popular electric furnaces is the Goodman brand. If you have a Goodman electric furnace and are having issues with it, I recommend reading through our Complete Goodman Furnace Troubleshooting Guide.
Steve Rajeckas is an HVAC hobbyist with an avid interest in learning innovative ways to keep rooms, buildings, and everything else at the optimal temperature. When he’s not working on new posts for Temperature Master, he can be found reading books or exploring the outdoors.