Hello Friends!
Hey everyone, Tony back at it again. Today we’re focusing on the unsung heroes of your electric furnace—the sequencers and relays. These components control when heating elements kick in and how your blower behaves. When they malfunction, you might get no heat, short cycling, or fan issues. But don’t sweat it—I’ll walk you through how these parts operate, how to test them, and how to replace them with confidence. Let’s get our hands dirty and fix some furnaces. 🔧
1. Furnace Not Turning On? Start with the Basics
This might sound obvious, but I can’t tell you how many times I’ve pulled up to a “broken furnace” and found a tripped breaker. Before diving into advanced diagnostics, start with these quick checks:
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Make sure the thermostat is set to heat and the temperature is higher than the room temp. Replace the batteries if needed.
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Check the furnace disconnect switch—it may look like a light switch near the unit.
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Open your home’s breaker panel and see if the HVAC breaker is tripped. Flip it off and back on to reset it.
Still nothing? Then we’re going deeper.
🧠 Pro Tip: Some newer furnaces have control boards that flash error codes. Grab the manual and decode the blinking light—it’ll point you in the right direction.
Want to learn more about how thermostats can mess with your system? This Energy.gov guide breaks it down for beginners.
2. The Blower Motor Won’t Stop Running
If your furnace is constantly blowing air—even when it’s not heating—it usually means one of two things:
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The fan setting on your thermostat is set to “On” instead of “Auto.”
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The limit switch is stuck or malfunctioning.
That limit switch is a safety device that shuts the furnace off if it gets too hot. But if it breaks, it can leave the blower fan running 24/7. Some switches can be reset, while others need replacing. You can test this with a multimeter, but be careful—there’s live voltage in the system.
💡 Check out this practical explanation of how furnace fan limit switches work for a deeper dive.
3. No Heat? Check the Sequencer and Heating Elements 🔥
If the air is blowing but it’s cold, you’re likely dealing with one of two issues:
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A burned-out heating element (or multiple).
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A faulty sequencer, which controls the order in which the heating elements power on.
To test this, you’ll need a multimeter. Start by cutting power to the furnace and opening the access panel. Visually inspect the heating coils for breaks or damage. Then use the multimeter to test for continuity.
If you don’t have experience working with electrical components, this is where I recommend calling in help. Mishandling a heating element can lead to burns or electrical shock.
Want to geek out? HVAC School’s breakdown of electric heat sequences explains how the whole process works.
4. Furnace Smells Weird? Here’s What’s Going On
Electric furnaces aren’t supposed to smell like anything. If you catch a whiff of something off, here’s what it could mean:
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Burning Dust: This is normal during the first few heating cycles of the season. Dust settles on the coils and burns off.
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Electrical Burning: Smells like melting plastic? That could be a shorted wire, burned terminal, or overheating part.
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Musty Odor: Mold or mildew in your ductwork or furnace.
If it smells like something is on fire, kill the power and inspect the wiring. Don’t risk a full electrical fire. Here’s a helpful guide from Family Handyman on common furnace odors and how to handle them.
👃 Keep a carbon monoxide detector near your HVAC system—even electric furnaces can share ductwork with gas units.
5. Furnace Turns On, Then Shuts Off Too Soon (Short Cycling)
Short cycling is a classic headache. The furnace kicks on, runs for a minute or two, then shuts off—and repeats. This wears out parts fast and spikes your energy bills.
Possible causes include:
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Clogged filters causing overheating and tripping safety limits.
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A faulty thermostat sending false signals.
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Malfunctioning high-limit switches or control boards.
First, change the filter—seriously, do it. Then test the thermostat (or temporarily replace it). If that doesn’t fix it, you may have a deeper issue inside the unit.
Want a second opinion? Check out Bob Vila’s troubleshooting guide—his team breaks it down nicely.
6. Troubleshooting Electric Furnaces with Error Codes and Flashing Lights 💡
Modern electric furnaces often come with built-in diagnostics—LED lights that flash in specific patterns when something goes wrong. These can point you toward problems like:
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Faulty blower motors
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Bad sequencers
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Transformer issues
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Low voltage
You’ll need the furnace model number and the service manual, which you can usually find on the inside of the access panel or online. Look up the error code sequence and follow the diagnostic tree.
Pro tip: Bookmark this Lennox troubleshooting resource for interpreting codes on many popular units.
7. Safety Reminders for DIY Troubleshooting
Electric furnaces are safer than gas units in a lot of ways—but you’re still dealing with 240 volts of power, and that’s no joke. Follow these safety tips:
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Always shut off power at the breaker before opening panels.
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Use a voltage tester before touching anything.
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Replace panels and covers securely before restoring power.
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Don’t touch heating elements or transformers unless you know what you’re doing.
Also, if you're not using a certified multimeter or have trouble reading wiring diagrams, it’s okay to stop and call a tech. YouTube tutorials don’t replace real training.
8. When to Repair vs. When to Replace
Sometimes it's just not worth chasing ghost problems anymore. If your furnace is 15+ years old, and you’re constantly replacing sequencers, motors, or contactors, it might be time for a full replacement.
Signs it's time to replace:
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Unit cycles too frequently, even after repairs.
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Strange sounds that persist after maintenance.
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Heat output has dropped significantly.
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Repairs cost more than 30–50% of a new unit.
Looking for a dependable replacement? The Furnace Outlet’s Electric Furnace Collection has models ready to ship, plus specs that’ll help you match size and voltage to your home.
Final Thoughts From Tony 🧰
Alright, if you've stuck with me this long, chances are you're dealing with a finicky electric furnace and you're trying to get things squared away without calling in the cavalry. Good on you.
But look—I’ll be straight with you: if you’re not sure what’s wrong, don’t just start yanking wires and replacing parts hoping to get lucky. Use your multimeter. Pay attention to error codes. And when in doubt, don’t be afraid to call a local pro.
And hey, if your furnace has seen better days and it's time to make a clean break, you can check out a solid lineup of reliable replacements over at The Furnace Outlet. No pressure—just good gear.
Need to know more about electric furnace wiring? Visit my guide: From Breaker Box to Blower Motor.
Stay sharp, stay safe, and don’t forget to flip that breaker before you dive in. 😎
Catch ya next time.
—Tony the trusted tech!
