Electric Furnace Not Heating? 7 Causes & DIY Fixes

How Electric Furnaces Work (Quick Overview)

Before troubleshooting, it helps to understand how your electric furnace heats your home:

1. Thermostat calls for heat – When room temperature drops below your set point, the thermostat sends a signal to the furnace.
2. Sequencer activates elements – The sequencer turns on heating elements one at a time (not all at once) to prevent electrical overload.
3. Elements heat up – Electric resistance coils (like a giant toaster) heat to red-hot temperatures.
4. Blower circulates air – The blower motor pushes air over the hot elements and through your ductwork.
5. Limit switch monitors safety – If temperatures get too high, the limit switch shuts everything down to prevent fires.

A problem at any step in this process can result in your electric furnace not heating. Let's diagnose each one.

A dirty air filter is the #1 cause of electric furnace problems. Here's why: when the filter is clogged, airflow is restricted. The heating elements get too hot because there's no air moving over them. The high-limit safety switch then shuts down the furnace to prevent a fire.

Symptoms:

• Furnace runs briefly, then shuts off
• Blower runs but no heat comes out
• Furnace cycles on and off frequently (short cycling)
• Burning smell when furnace runs

How to Fix:

1. Locate your air filter (usually in the return air duct or furnace cabinet)
2. Pull out the filter and hold it up to light
3. If you can't see light through it, it's clogged
4. Replace with a new filter of the same size (check the edge for dimensions)
5. Wait 30 minutes for the limit switch to reset, then try the furnace again

Electric furnaces typically use two circuit breakers—one for the blower motor and one (or two) for the heating elements. If just the heating element breaker trips, the blower can run while producing no heat.

How to Check:

1. Go to your electrical panel
2. Look for breakers labeled "Furnace," "HVAC," or "Heat"
3. A tripped breaker will be in the middle position (not fully ON or OFF)
4. Turn it all the way OFF, then back ON
5. Also check the disconnect switch at the furnace (usually a lever or switch nearby)

Sometimes the problem isn't the furnace at all—it's the thermostat not sending the right signals.

Things to Check:

• Mode setting: Make sure it's set to "HEAT" not "COOL" or "OFF"
• Fan setting: Set to "AUTO" not "ON" (ON runs the blower without heat)
• Temperature: Set higher than current room temperature
• Batteries: If battery-powered, replace them (dead batteries = no heat signal)
• Schedule: Check programmed schedules that might be keeping the temp low
• Location: Is the thermostat in direct sunlight or near a heat source? It may think the house is warmer than it is.

Test Your Thermostat:

1. Set the temperature 5 degrees higher than the current reading
2. You should hear a click from the thermostat
3. Within a minute, you should hear the furnace start
4. If nothing happens, the thermostat may need replacement or there's a wiring issue

Electric furnaces have 2-5 heating elements (depending on size). If one fails, you'll get reduced heat. If multiple fail, you may get no heat at all.

Symptoms of Failed Elements:

• Furnace runs but house doesn't get warm enough
• Some vents blow warm air, others blow cool
• Burning smell when furnace runs
• Higher electric bills (remaining elements work harder)
• Visual damage: discolored, warped, or broken coils

Why You Need a Professional:

Testing and replacing heating elements requires working with 240V electricity and using specialized tools like multimeters to test continuity and resistance. This is not a DIY job.

Schedule electric furnace repair →

The sequencer is a critical component that turns heating elements on one at a time. Without it, either all elements would turn on at once (tripping breakers) or none would turn on at all.

Symptoms of a Bad Sequencer:

• No heat at all (sequencer isn't triggering any elements)
• Only partial heat (some elements working, others not)
• Elements won't turn off (sequencer stuck in "on" position)
• Breakers trip when furnace starts (all elements energizing at once)

Sequencer testing requires a multimeter and knowledge of the specific staging sequence. A faulty sequencer is one of the most common causes of "furnace runs but no heat" that requires professional repair.

The high-limit switch is a safety device that shuts off the heating elements if temperatures inside the furnace get dangerously high. It's designed to prevent fires.

Why It Trips:

• Clogged air filter (most common—see #1)
• Blocked vents or registers in your home
• Failing blower motor not moving enough air
• Faulty limit switch itself

How to Reset:

1. Turn off the furnace and let it cool for 30 minutes
2. Replace the air filter if dirty
3. Make sure all vents in your home are open
4. Turn the furnace back on
5. If it trips again, call a professional—there's an underlying issue

The blower motor pushes heated air through your ducts. Without it, heat builds up in the furnace (tripping the limit switch) and no warm air reaches your rooms.

Symptoms:

• No air coming from vents (hot or cold)
• Weak airflow from vents
• Humming, squealing, or grinding noises
• Furnace overheats and shuts down quickly
• Burning smell from motor overheating

Quick Check:

Set your thermostat fan to "ON" (not auto). If you don't feel any air from the vents within a minute, the blower motor isn't working. Sometimes it's just a bad capacitor (less expensive to replace), not the entire motor.

When to Call a Professional

Troubleshooting Summary Checklist

Frequently Asked Questions

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