Most furnaces give you some warning before they stop working. A few signs mean you should call right away: a carbon monoxide alarm, the smell of gas, a burning smell that won’t clear, or no heat at all in freezing weather. Others, like short cycling or uneven heat from room to room, aren’t emergencies but shouldn’t ride out the whole season. The reassuring part: most of what our technicians find on a furnace repair call turns out to be small.
Aspen Aire has serviced furnaces in Des Moines and Ankeny since 2006, and the pattern holds up year after year. Homeowners who call when they first notice something usually need a part, a cleaning, or an adjustment. The ones who wait until the coldest week of January tend to need more. Here’s how to tell which group your furnace belongs in.
Furnace Warning Signs That Mean Call Right Away
These five signs point to a safety issue or a system that has already stopped doing its job. Don’t wait on any of them.
- Your carbon monoxide alarm sounds. Get everyone outside to fresh air first, then call for help. Carbon monoxide is colorless and odorless, and the CDC describes its symptoms as flu-like. That’s what makes it easy to dismiss. Take a sounding alarm seriously every time. Sometimes the cause is a car warming up in an attached garage rather than the furnace. Our post on carbon monoxide safety covers what to check.
- You smell gas. A rotten egg or sulfur smell near the furnace means leave the house and call your gas utility from outside. Don’t flip switches on your way out.
- A burning or scorched smell that doesn’t fade. Some dust burning off during the first run of the season is normal, and it clears within an hour or so. A sharp electrical or plastic smell, or a burning smell that keeps coming back, is not.
- No heat at all during a cold snap. A furnace that won’t produce heat below freezing is an Iowa emergency, both for your comfort and for your pipes. Aspen Aire answers heating calls 24 hours a day, seven days a week.
- Loud banging, grinding, or screeching. Sounds like these usually mean a moving part is failing. Shutting the system off and calling is almost always cheaper than letting it run to failure.
Warning Signs That Can Wait a Few Days, but Not a Season
The next group is easy to live with, which is exactly why these tend to get ignored until something bigger happens. None of them is an emergency. All of them are worth a service call in the next week or two, while the fix is still small.
- Short cycling. Your furnace turns on, runs briefly, shuts off, and starts again a few minutes later. This wears on the system and keeps your home from ever settling at a steady temperature.
- Rooms that never reach the thermostat setting. If the bedrooms stay cool while the main floor is comfortable, something is off in airflow, ductwork, or system capacity.
- Weak airflow from the vents. Hold a hand over a register. If the air is moving noticeably slower than it used to, the system is working harder than it should.
- A heating bill that keeps climbing. Rate changes and cold snaps explain a lot. A bill that climbs year over year on similar weather usually points to lost efficiency. The U.S. Department of Energy notes that regular maintenance is what keeps a furnace operating at its rated efficiency.
- A delay before the furnace kicks on. Clicking, a pause, then ignition. It may still heat your home fine, but the delay says something in the ignition sequence is struggling.
- Visible rust or moisture around the base. Worth having looked at before it spreads to something structural.
What These Symptoms Usually Turn Out to Be
Symptoms rarely map one-to-one to a single cause, but after nearly 20 years of service calls in Central Iowa, a few patterns come up again and again:
- Short cycling most often traces back to a clogged filter, a dirty flame sensor, or a thermostat placed where it reads the wrong temperature.
- Weak airflow is usually a filter or a blower issue. Filters are the cheapest fix in heating. Our guide on how often to change your furnace filter covers the schedule.
- Uneven heat between rooms tends to be ductwork, register balance, or a system sized for a different floor plan.
- Delayed ignition often comes down to a dirty burner, a worn igniter, or a flame sensor that needs cleaning.
- Rising bills with no other symptom usually mean the system is running longer to hit the same temperature. That points back to airflow, combustion efficiency, or a furnace nearing the end of its life.
Our technicians diagnose and repair every gas and electric furnace brand. The fix doesn’t depend on who made your equipment.
When a Repair Turns Into a Replacement Conversation
Repair is the right answer most of the time. A few situations are worth an honest conversation about replacement instead:
- The furnace is past 15 to 20 years old and the repair is a major component.
- You’ve paid for two or more repairs in a single heating season.
- A technician finds a cracked heat exchanger, which is a safety issue rather than a maintenance item.
- Bills keep climbing even after the system has been serviced.
None of those automatically means replace. They mean you should get real numbers for both paths before deciding. Our technicians explain what’s wrong and what it costs before any work starts. That’s part of the commitment we make to every customer. No gimmicks, no hidden fees, and no recommending something you don’t need.
A Few Quick Checks Before You Call
If your furnace isn’t running and nothing on the urgent list applies, four things are worth checking first. They resolve a surprising number of calls:
- Confirm the thermostat is set to Heat and to a temperature above the current room temperature. Replace the batteries if the screen is blank.
- Check the air filter. A filter packed with dust restricts airflow enough to shut a furnace down.
- Check the breaker. If it has tripped, reset it once. If it trips again immediately, leave it off and call.
- Make sure the furnace switch, which looks like an ordinary light switch near the unit, is in the on position.
For the full walkthrough, including what to look for at the gas valve, see our step-by-step furnace troubleshooting guide. If you’ve worked through those checks and the furnace still isn’t heating, the next step is a technician.
Furnace Repair in Des Moines, Ankeny, and the Surrounding Metro
Aspen Aire provides furnace repair 24 hours a day, seven days a week across Central Iowa. When you call after hours, our answering service reaches a technician and we get someone out as quickly as possible. We service Des Moines, Ankeny, West Des Moines, Urbandale, Waukee, and the rest of our service area.
The best way to avoid a repair call altogether is to catch small issues early. A fall furnace tune-up is a full inspection, cleaning, and safety test. Preseason savings are running now on our current offers page. Club Membership includes a fall furnace check and a spring AC tune-up every year. Members also get priority scheduling and regular service rates around the clock. Nobody has to remember to book it.
Furnace Repair FAQs
What are the first signs a furnace needs repair?
The earliest signs are usually subtle: short cycling, weak airflow, a delay before the furnace kicks on, or rooms that never reach the thermostat setting. These aren’t emergencies, but they’re the point at which a repair is still small and inexpensive.
Is a furnace that short cycles an emergency?
No, but it shouldn’t be ignored. Short cycling usually comes from a clogged filter, a dirty flame sensor, or a thermostat reading the wrong temperature. Left alone through a full Iowa winter, the extra wear can shorten the life of the system.
My carbon monoxide detector went off. Does that mean my furnace needs repair?
Sometimes, and it always deserves a response. Get everyone to fresh air first. The Consumer Product Safety Commission recommends CO alarms on every level of the home and outside sleeping areas. In our experience the cause is sometimes a vehicle warming up in an attached garage rather than the furnace. The only way to know is to have the system checked.
How quickly can I get furnace repair in Des Moines?
Aspen Aire answers heating calls 24 hours a day, seven days a week, including nights, weekends, and holidays. Call 515-257-8370 and we’ll get a technician to you as quickly as possible. Club Members receive priority scheduling.
Is it worth repairing an older furnace?
Often, yes. Age alone doesn’t rule out a repair. It becomes a closer call when the furnace is past 15 to 20 years old. That’s also true when the repair involves a major component, or when you’ve already paid for repairs this season. Your technician will give you the numbers for both repair and replacement so you can decide.
The Bottom Line
Furnaces tend to tell you something is wrong before they quit. A carbon monoxide alarm, a gas or burning smell, loud mechanical noise, or no heat in freezing weather all mean call now. Short cycling, uneven heat, weak airflow, and creeping energy bills mean call soon. Either way, the fix is almost always smaller and cheaper the earlier it’s found.
