There’s nothing quite like that sinking feeling when you turn down your thermostat on a cold Minnesota morning, expecting to hear your furnace kick on, and… nothing happens. Before you panic and start bundling up in layers, take a deep breath. Many furnace issues have simple solutions that you can check yourself before calling in the pros. Let’s walk through some of the most common culprits when your furnace decides to take an unexpected day off.

Start With the Basics: Your Thermostat

It might sound obvious, but you’d be surprised how often the thermostat is the real troublemaker. First, make sure it’s actually set to “heat” mode and not stuck on “cool” or “off.” Check that the temperature setting is higher than your current room temperature—your furnace won’t turn on if it thinks the house is already warm enough.

If you have a programmable or smart thermostat, the batteries might be dead. Swap them out with fresh ones and see if that solves the problem. Also, take a quick look at the thermostat itself. Is it level on the wall? Sometimes a crooked thermostat can cause reading errors.

Check Your Circuit Breaker

Head down to your electrical panel and look for any tripped breakers. Your furnace has its own dedicated circuit, and if something caused it to trip, your system won’t get the power it needs to run. A tripped breaker will be in the middle position or switched to “off.” Flip it all the way off, then back on again. If it trips again immediately, that’s a sign of a bigger electrical issue that needs professional attention.

Don’t forget to check if there’s a power switch near your furnace—it usually looks like a regular light switch and might be on the side of the unit or on a nearby wall. Someone might have accidentally flipped it off while moving things around in your utility room.

Take a Look at Your Air Filter

A clogged air filter is one of the most common reasons furnaces shut down. When airflow gets restricted, your system can overheat and trigger a safety switch that turns everything off. Pull out your filter and hold it up to the light. If you can’t see through it, it’s time for a replacement.

During our harsh Minnesota winters, you should be checking your filter monthly and changing it every one to three months, depending on your household. If you have pets or allergies, you might need to change it even more frequently.

Inspect Your Pilot Light or Ignitor

For older furnaces with a pilot light, check if the flame is lit. It should be a steady blue flame. If it’s out, your owner’s manual will have instructions for relighting it safely. If the pilot won’t stay lit or if you smell gas, turn off the gas supply and call for help right away.

Newer furnaces use electronic ignitors instead of pilot lights. You might hear clicking sounds when the furnace tries to start. If you hear clicking but no ignition, the ignitor could be faulty.

Look at Your Vents and Registers

Walk around your home and make sure all your supply vents are open and unblocked. Furniture, curtains, or storage boxes pushed against vents can restrict airflow enough to cause your system to shut down. You need at least 75% of your vents open for proper system operation.

Check for Error Codes

Many modern furnaces have a diagnostic system that flashes LED lights in specific patterns when something’s wrong. Your furnace’s access panel should have a legend explaining what different flash patterns mean. These codes can help narrow down the problem and give you useful information to share with a technician.

When to Call in the Experts

If you’ve checked all these common issues and your furnace still won’t start, or if you’re uncomfortable performing any of these checks yourself, it’s time to bring in a professional. Some problems—like failed blower motors, cracked heat exchangers, or complex electrical issues—require specialized knowledge and tools to diagnose and repair safely.

Don’t let a broken furnace leave you in the cold! Our experienced team here in Blaine understands Minnesota winters and knows how important reliable heat is for your family’s comfort and safety. We offer fast, friendly service and can usually get your system up and running the same day. Give us a call, and let’s get your home warm again!