Some warning signs are: uneven heating, cold spots, weak airflow, strange noises (popping, rattling, clicking), burning or unusual smells, frequent cycling on and off, a heater that won’t start, or rising energy bills without a change in usage.

Possible causes include a faulty thermostat, a blocked or dirty air filter, issues with the heat exchanger, or gas or ignition problems. If warm air isn’t making it through, it may also be ductwork leaks or problems with the blower motor.

Short cycling (system turning on and off too rapidly) can be caused by a dirty air filter, thermostat issues, overheating, or airflow obstructions. It stresses the system and reduces efficiency. Prompt repair prevents further damage.

Uneven heating can stem from duct leaks, improper duct design, insulation issues, or uneven airflow. Also, failing blower motors or blocked vents can cause some rooms to get less heat.

If your heater is over 15 years old, has had frequent breakdowns, isn’t energy efficient, or repairs are becoming very costly, replacing may be more cost-effective. A new, high-efficiency unit could lower your energy bills and provide more reliable service long term.

As soon as you notice unusual signs—cold air, odd noises, smells, or failure to heat—it’s best to call for repair promptly. Delaying can lead to more extensive damage, higher repair costs, or complete system failure.