When your heater runs but the air coming from vents feels cool, it’s frustrating — and it can happen for several reasons, some simple and some requiring professional help. Before you call for service, there are a few troubleshooting steps you can take to identify common issues and possibly restore warmth quickly.
Check this list if your heater isn’t blowing warm air
First, check the thermostat. Ensure it’s set to heat and the temperature is higher than the current room temperature. If your thermostat uses batteries, replace them; a weak battery can cause the system to behave erratically. If you have a programmable or smart thermostat, verify the schedule and settings haven’t been changed accidentally.
Next, inspect the air filter. A dirty or clogged filter restricts airflow and can cause the furnace to overheat and shut down the burner while the blower continues to run, producing cool air. Replace disposable filters or clean reusable ones according to manufacturer instructions. While you’re at it, make sure all supply and return vents are open and unobstructed; closed vents can upset system balance and reduce heat delivery.
Check the pilot light or ignition system on gas furnaces. A pilot light that’s out or an ignition failure will prevent the burner from producing heat. If you’re comfortable and it’s safe to do so, relight the pilot following the manufacturer’s instructions. If the pilot won’t stay lit or the ignition keeps failing, call a licensed technician — these issues can indicate a faulty thermocouple, gas valve, or ignition module.
If your system cycles on but the blower runs continuously without heat, the furnace may be in a safety lockout due to overheating, blocked vents, or a malfunctioning limit switch. Strange noises, burning smells, or visible rust are signs to stop using the system and call for service. For heat pumps, cold outdoor temperatures can reduce efficiency; many systems have auxiliary heat strips that engage when needed — check whether those are functioning.
Regular maintenance prevents many of these issues. Annual inspections, filter changes, and cleaning by a qualified technician keep systems running reliably. If troubleshooting doesn’t restore warm air, contact Lakewood Plumbing for fast, professional heating diagnostics and repairs. Visit lakewoodplumbing.com or call 303-233-7007 to schedule service and get your home warm again.
