7 Signs Your Furnace Might Not Make It Through Winter

Don’t Get Left in the Cold — Know When It’s Time for a Repair with These Furnace Winter Warning Signs

Winter in Idaho can be unpredictable — freezing nights, snow-packed mornings, and months of heavy furnace use. The last thing any homeowner wants is a system failure in the middle of a cold snap.

At Sermon Service & Electric, we’ve seen it time and again: Blackfoot furnace repair calls spike just when temperatures drop below freezing. The good news? Most furnace breakdowns give off warning signs long before the heat stops completely.

Here are 7 furnace winter warning signs your that it might not make it through the winter — and what you can do about them.

1. Unusual Noises — Clanging, Rattling, or Whining

If your furnace suddenly sounds like it’s hosting a rock concert, it’s time to pay attention.
Grinding or banging noises can mean loose parts, a worn-out motor, or issues with your blower assembly.

Don’t ignore it — small mechanical problems caught early can often be fixed with a simple tune-up before they turn into a system failure.

2. Uneven Heating Around the House

When one room feels like a sauna and another like an icebox, it’s a red flag.
Uneven heat often points to airflow or duct issues, or a furnace that’s starting to lose efficiency.

We see this often in Rexburg heating and plumbing calls — especially in older homes that haven’t had ductwork serviced in years. Balancing your system now can save major discomfort later.

3. Your Furnace Struggles to Keep Up

If your system runs constantly but can’t reach your thermostat’s set temperature, it’s likely fighting an uphill battle.
The cause could be a dirty filter, weak ignition system, or — in older units — simply loss of performance due to age.

In Ashton heating and plumbing service areas, where winter temperatures drop fast, furnaces that “run endlessly” are often on their last legs.

4. Rising Energy Bills

A sudden jump in your heating bill (without a change in usage) is a classic sign of declining furnace efficiency.
Older systems need more fuel or power to produce the same level of heat — which means you’re paying more for less comfort.

Sometimes a quick repair can restore efficiency, but if bills keep climbing month after month, it’s time to start planning for replacement.

5. Strange Smells or Poor Air Quality

If you notice musty, dusty, or even burning odors when your furnace kicks on, it’s worth scheduling a professional inspection.
This can signal dirty burners, a failing heat exchanger, or a clogged filter circulating particles into your home’s air.

Routine maintenance keeps your system — and your family’s air — clean and safe.

6. Frequent Cycling or Short Runs

When your furnace turns on and off rapidly (known as short cycling), it’s often struggling to regulate temperature properly.
This can be caused by a failing thermostat, overheating, or airflow blockages — and it’s a warning sign of a system under stress.

Short cycling increases wear and tear, shortening your system’s lifespan if left unchecked.

7. The Furnace Is More Than 15 Years Old

Even the best furnaces have a limit.
If yours is approaching or past the 15-year mark, it’s likely running at reduced efficiency and could fail without warning.
Replacing it before peak winter ensures you’re not left without heat during subzero nights.

Don’t Wait Until It Breaks

If any of these signs sound familiar, it’s time for a furnace inspection before winter hits full force.
We see the highest number of Blackfoot furnace repair requests right after the first hard freeze — but most could have been prevented with early maintenance.

Homeowners in Rexburg, Ashton, and across Southeast Idaho can protect their comfort (and their wallets) by addressing small issues now, before they become emergencies.

Stay Warm All Winter Long

A quick service call today can mean a season of worry-free comfort tomorrow.
Schedule your furnace inspection or repair now to ensure these furnace winter warning signs make it through winter — safely, efficiently, and reliably.

Call or schedule online for expert furnace repair and maintenance throughout Blackfoot, Rexburg, Ashton, and the surrounding Idaho communities.