Why Is My Electric Furnace Blowing Cold Air?

Electric furnaces are often energy-efficient, but they can sometimes malfunction. If your electric furnace is blowing cold air or won’t heat up, there’s likely a mechanical issue or two. 

Your electric furnace is blowing cold air because the filter needs to be changed, the ductwork is leaking, or the furnace is not getting enough electricity. Additionally, it could be caused by your furnace’s built-in thermostat not working properly.

Throughout this post, I’ll show you why your electric furnace isn’t blowing hot air and what you can do about it. I’ll also provide you with a few preventative maintenance tips.

1. Electrical Issues

If your electric furnace is wired improperly or the control board isn’t working, it won’t be able to adjust the temperature. Usually, the furnace should have enough power to blow air out of the vents, so faulty wiring can cause it to not heat anything. You’ll end up pushing air through the ducts, making your home feel stale or muggy.

How To Fix?

Flip the breaker or unplug your furnace if it’s plugged into a wall outlet. Never try to work on an electric furnace when it has electricity going through it (unless you’re testing the parts for voltage and wattage). Wait a few minutes for the capacitor to discharge if you have to be near it.

If you’re not 100% sure of your ability to fix electrical appliances, I strongly suggest contacting a professional to help you diagnose and repair these issues. Not only will you be assured of a clean repair job, but you’ll also ensure your safety and that of your household members.  

Read: Why Furnace Keeps Running And No Heat?

2. Air Duct Leaks and Clogs

Damaged air ducts are one of the most common causes of central heating not working. When there’s a hole in the duct, some of the heat escapes through it. This worsens if the leak or tear is closer to the electric furnace. Debris and mold buildup can likewise cause air duct leaks and clogs.

How To Fix?

Pressuring the air ducts will remove excess debris, but you might have to patch them with aluminum tape if there are leaks. Most technicians will clean air ducts in sections because they often come apart. Vacuuming the ducts is an excellent way to eliminate mold spores, preventing them from spreading and clogging the vents.

Read: Cracked Heat Exchanger In Furnace – How To Troubleshoot?

3. Clogged or Broken Filters

Every furnace has a built-in filter. Some of them are reusable, while others are single-use filters. If the filter is clogged with debris or there’s a tear in the mesh, it needs to be replaced or repaired. (Note: Furnace filters have different locations depending on the furnace. Check the user’s manual to find yours.)

How To Fix?

Inspect, clean, or repair the air filter. A clogged or damaged filter is one of the main reasons your electric furnace can’t blow hot air. Pull the filter out of the vent, then wash it in the sink or with a hose. Never reuse single-use filters because they can break apart.

Read: Why Furnace Is Leaking Water?

4. Malfunctioning Thermostat

The thermostat has a sensor in the furnace. Some of them have sensors in the air ducts to provide accurate readings. If these sensors are broken, they’ll tell the thermostat that the air is already hot enough, making it think it doesn’t need to produce hot air.

How To Fix?

Test each sensor with a multimeter or a voltmeter to ensure it’s getting enough power. After turning on the circuit breaker, you can place the hot and neutral probes on the sensors to know if they’re getting either 120v or 220v, depending on the breaker they’re connected to. 

I like the Klein Tools 69149P Electrical Test Kit with Digital Multimeter (available on Amazon.com). The kit has everything you need to accurately determine if your thermostat sensor (as well as other appliances in your home) is working properly. The green light will tell you that the multimeter is working, while the red light will indicate whether there’s voltage in the appliance you’re testing. 

If all signs indicate that they have power but aren’t working for some reason, replace the affected sensors.

Read: Does Closing AC Vents Save Electricity?

5. Vent Problems

If your air vents are closed, broken, clogged, or otherwise hindered, they won’t be able to produce hot air. A lot of heat will absorb into the metal blades and go back into the HVAC ducts. This process can cause leaks and overheated furnaces in the long run.

How To Fix?

First, make sure the furnace is turned off so you can work on the vents safely. Next, locate the vents in your home and unscrew the grills to open them. Since the vents are small, narrow spaces, the best way to clean them is with a powerful vacuum. You can drop by your local hardware store and ask them about vacuums that work best for cleaning vents. 

6. Drain Line Is Dirty

If the drain line is filled with condensation, it will also cause your electric furnace to blow cold air. The drain line should be located at the bottom of your furnace.

How To Fix?

Remove and wash the drain line to let condensation drain properly. Locate the pipe and the drain pan at the bottom of the unit, then wash both pieces with a garden hose. You can also scrub them with soap if necessary. Make sure you dry them thoroughly before you use the furnace again. 

Read: How To Reset Lennox Furnace?

Preventive Maintenance for Electric Furnaces

There are many ways to prevent your electric furnace from blowing cold air after repairing it. 

• Clean the vents regularly. Clean the filter every three to six months or as instructed by the manufacturer. Use a stiff brush to clean each of the vents around your home. This will prevent mold and other debris from clogging the airways. It’ll also ensure that the filter doesn’t get clogged too quickly. 
• Make sure the filter is pointed in the correct direction. The arrows should face outward. Otherwise, it won’t filter out the dust and debris properly. 
• Scrub and maintain the cabinet or garage around the electric furnace. Renaud Electric recommends cleaning the storage cabinet because it prevents all of the debris from clogging the filter. 
• Inspect your air ducts annually or hire a technician. Leaks should be patched with aluminum tape, mold should be removed immediately, and broken connections should be replaced. Some technicians offer multi-month warranties that could pay dividends if something goes wrong.
• Turn off your thermostat when you’re not home. If your thermostat runs around the clock, it’ll cause a lot more wear and tear. This process eventually leads to damaged sensors, control boards, and capacitors. You can use smart apps with many modern thermostats if you want a warm home before you arrive.
• Maintain your home’s ambient humidity. Keep the humidity between 35% to 45% with dehumidifiers and humidifiers. This will prevent mold growth, mildew, rot,  rust, corrosion, and other problems that could harm your electric furnace.

Final Thoughts

If your electric furnace isn’t heating your home, it’s time to take action. Dirty filters and leaky air ducts have other consequences besides preventing your house from feeling warm. For example, they can cause expensive damage to the drywall, wood rot, mold growth, and more. Following the aforementioned suggestions will keep your HVAC system in good shape.