More often than not, furnaces will develop problems when we least expect them. If you have an electric furnace that no longer blows hot air, you must look into it until a certified HVAC technician comes for further servicing.
What makes an electric furnace not blow hot air anymore
As there can be several reasons your electric furnace blows cold and there is no air inside, we need to present them all, along with the possible fixes.
The thermostat is set to a fan or AC
The thermostat has several settings, including Cool (it typically means AC) and Fan. If the thermostat isn’t set to Heat, it will blow cold and not hot air on any of these two.
The fix
Simply check out the thermostat and switch it to Heat if it’s not set right.
The contactor is faulty
With electric furnaces, a contactor (it’s a heavy-duty relay) will turn on the heating elements. When the contacts get pitted and don’t connect, the coils won’t get energized, so that the furnace won’t heat the air. You can reset the contacts by turning them on and off. However, with many models, replacement is the only solution if they begin to fail.
You have to replace the contactor (the electrical relay), which is between $30 to $100. If you are skilled and experienced, you can try to replace the contactor yourself.
Loosen the screws that keep the contactor in place
Disconnect the wiring
Remove the current contactor
Install the new contactor
Needless to say, the new contactor has the same amps and volts as the defective one. Check out the label on the contactor to see what you need to buy. To ease out the replacement, you should take a picture of the wiring before you remove the old contactor. It’s a visual tool to help you attach the wires to the new contactor.
The thermostat is defective
Your electric furnace isn’t always the problem; sometimes, a defective thermostat can make the furnace not perform as expected. When the thermostat is defective, it can make the fan run without the coils being energized to generate heat.
The fix
If the thermostat is faulty, you need a new thermostat. We recommend you contact a certified HVAC technician to verify the system before concluding that the broken thermostat is the cause for your furnace not blowing hot air.
The filter or the coils are dirty
When the furnace filter is dirty, you might feel that the electric furnace blows cold air, even hot air. A dirty filter will obstruct proper airflow, so the heated air won’t come out. The air will be heated, but it’s not going to be enough to warm a room, rendering you to feel it’s blowing cold air. Dirty heating coils will also make the furnace heat inefficiently.
The fix
Check out the furnace filter in your furnace or air handler. If it’s dirty or you didn’t replace it for a long time, you should replace it with a new one. If it’s a permanent filter, check out the manual instructions to clean it.
General guidance on cleaning coils comes next:
Open the cabinet and take off the door
Find the coils
Unbolt the coils and slide them out
Use a shop vacuum hose to vacuum off the coils gently
If possible, get the hose into the cabinet to remove debris and dust
One or several coils are burned out
Electric furnaces, like heat pump air handlers, use electric resistance heating coils. The electric coil will burn out with regular wear or be blown by a power surge (it happens a lot). If the coil is burned out, the furnace’s blower might still operate, but it will blow cool air.
The fix
There’s just one solution: replace the coil. If your furnace is old and one coil is burned out, you should replace them. It’s only a matter of time until all coils will burn out. When you know your way around household chores, you can try replacing the electric coils yourself. Since you will work with electricity, you must be sure what you’re doing. You need to turn off the circuit to the furnace at the electric panel. Make sure that nobody turns it back on and lock the box. If this sounds like a stretch, call the pros to replace the coils on your electric furnace.
The circuit controlling the heating coils has tripped, or it’s off
Check the electric panel to detect the circuit controlling the electric furnace heating elements. There should be labels.
The fix
If you cannot find a label, look for the circuit in the Off position or an “in-between” tripped position. Switch it to the On position and wait for the furnace to start heating. If the circuit has tripped, you need to turn it off before turning it back on. Should the circuit keeps tripping every time you flip it back on, something is wrong with the furnace, such as a short in one of the elements or the wiring.
Ducts are leaking
When the furnace is running and generating heat, but you cannot feel it, air might be leaking in the basement, attic, or other areas. Leaking ducts only get worse as time goes by; it can be long until you notice.
Other times, the connection or joint in the ductwork disconnect simultaneously, so warm air won’t circulate through the vents. Should the blower run, but not much air will come out of the vents, broken or leaking ductwork are the most common cause.
The fix
Check out the exposed ducts in the attic, basement, and all the areas where you can visually inspect them. Do you notice gaps or disconnections? If you’re a DIY homeowner, you can easily fix the ductwork with some mastic or high-quality duct tape. Hold the duct together and tape it. Ask someone to help you to get the best results.
We want to remind you that all ductwork has to be insulated. Minimize energy losses in the duct by sealing and insulating all exposed ductwork, whether you have a problem with the electric furnace.
The heat sensor is faulty
Electric furnaces feature a heat sensor to make sure that the furnace generates heat. After the furnace has reached the desired temperature, the sensor will turn off the blower fan. When the sensor is defective, it might not inform the blower fan to shut off. As a result, the electric furnace will keep running without generating heat. Cold air will come out of the vents.
The fix
You have to check the temperature setting on the thermostat and the air temperature. Many digital thermostats will display both. For instance, this can be the problem when the thermostat’s set point is 74 degrees, the thermostat reads 74 or higher, and the blower is still operating.
Replacing the sensor is a job better left to the professionals. Contact an HVAC technician to inspect and fix the heat sensor.
Just wait for a few minutes
Electric coils heat up rather quickly. Even so, after the furnace blower starts, it will need to push cool air out of the ducts before it starts pushing the heated air through the vents. If your house is spacious, and the room you’re in is far from the furnace, it might take a few minutes until heated air reaches and flows through the vents.
The fix
Wait for several minutes for warm air to reach the vents and come through them. That doesn’t mean you should wait for half an hour. If warm air doesn’t come out after several minutes, you can go up to this article and review the possible causes and fixes.
