When your furnace is working properly, life just feels right—your home stays warm, the air moves quietly, and your energy bills don’t surprise you. But as systems age or go without maintenance, little warning signs start to appear. You might notice strange noises, odd smells, dustier air, or a drop in heat that leaves certain rooms colder than others. Some of these problems are easy to fix on your own, but others need a trained professional to keep your system safe and efficient.
Below, we’ll walk through some of the most common furnace issues we see in Brighton, Howell, Ann Arbor, Plymouth, Lansing, and across Southeast Michigan—plus what you can do before picking up the phone for help.
1. No Heat
If your furnace is blowing cool air—or no air at all—the first place to look is your thermostat. Make sure it’s set to Heat and Auto rather than Cool or Fan Only. If that looks right, bump up the temperature a few degrees to see if the system kicks on. A blank screen may mean you need to replace the thermostat batteries.
If everything checks out but your furnace still won’t start, it could be a deeper issue with the ignition, gas line, or control board. That’s when it’s time to call a technician for a closer look.
2. Poor Airflow or Dusty Air
If your home feels stuffy or your furnace seems to struggle moving air through the vents, the problem could be as simple as a dirty air filter. When the filter clogs with dust, pet hair, and debris, airflow drops and your system has to work harder to push heat through the ducts. That extra strain shortens the lifespan of your furnace and can even cause it to overheat and shut off early.
Replacing the filter every month or two—more often if you have pets or allergies—keeps the air cleaner and the furnace running efficiently. Also, make sure your vents are open and not blocked by furniture or curtains.
3. No Pilot Light or Ignition Failure
If your furnace won’t ignite or shuts off before it warms up, the cause could be in the pilot assembly, electronic ignition system, or gas supply. These parts are delicate and potentially dangerous to work on yourself. If there’s no visible flame or the furnace tries to start but fails, shut it off and let a professional handle the repair. Gas valves, ignition switches, and flame sensors require proper tools and safety checks to ensure your system runs correctly and safely.
4. Frequent Cycling
If your furnace keeps turning on and off in short bursts, that’s called “short cycling,” and it’s usually a sign something’s wrong. It can be caused by a dirty filter, an overheating safety switch, or even a thermostat installed too close to a heat source. Start by changing the filter and ensuring the vents are clear. If the problem continues, a technician can check for more serious issues before they cause unnecessary wear and tear on your system.
5. Furnace Won’t Power On
When your furnace doesn’t respond at all, start with the simple things. Check your breaker box and reset any tripped switches. Make sure the furnace’s power switch (it often looks like a light switch near the unit) is on, and that the front access panel is securely closed—some systems won’t run if it’s loose. If the system still won’t turn on, you may be dealing with an electrical or control board issue that requires professional help.
6. Strange Odors
If your furnace smells like burning metal the first time you turn it on, don’t panic. That’s often just dust burning off after sitting idle through summer. The smell should fade within a few hours.
But other odors are more serious. A rotten-egg or sulfur smell could mean a gas leak—leave your home immediately, avoid using electronics, and call 911 or your gas company from a safe location. If you smell something electrical or like burning plastic, shut off the furnace and schedule a service call right away. It may indicate overheating components or wiring issues that can become fire hazards.
7. Noisy Operation
All furnaces make a little noise—a soft click when the thermostat calls for heat or a gentle whoosh when the blower starts. But banging, rattling, or screeching sounds are red flags. Loose panels or bolts can cause rattles, while screeching often points to a worn motor bearing or belt. A loud boom or rumble can signal ignition or fuel problems. If you hear anything unusual, turn off the system and have it inspected before further damage occurs.
8) Water or Condensation Leaks
If you find water pooling around the base of your furnace, don’t ignore it. High-efficiency models create condensation that should drain through a small tube or pump. If that line clogs, water can back up and leak out. In standard-efficiency systems, water usually means something else—often a cracked heat exchanger or blocked exhaust vent. Either way, it’s a job for a professional before the damage spreads.
Simple Habits That Prevent Big Problems
A few small habits can keep your furnace running smoothly and help you avoid costly repairs. Change your air filter regularly and keep vents open throughout your home so air can move freely. Upgrading to a smart thermostat is another easy step—it helps balance your home’s temperature and saves energy at the same time. If you rely on oil or propane, monitor your fuel levels early in the season so you’re never caught off guard. Around the house, sealing up leaky doors and windows helps your furnace hold warmth longer and work less to keep up. And don’t forget to schedule a professional tune-up before winter hits. It’s the best way to catch worn parts, clean buildup, and make sure your system is safe and ready for the cold ahead.
Why Michigan Homeowners Choose AAA Service Network
For nearly 50 years, AAA Service Network has helped homeowners across Southeast Michigan stay warm, safe, and comfortable through long winters. Our NATE-certified technicians repair and maintain all types of heating systems, from gas and oil furnaces to boilers and heat pumps. We offer emergency service, free replacement estimates, and can help you take advantage of rebates and financing options when it’s time for an upgrade.
When your furnace needs attention—whether it’s making noise, blowing cold air, or refusing to start—trust the local team that’s been keeping Michigan homes warm for decades. Call AAA Service Network today to schedule your repair, tune-up, or installation.