Why is my heating system blowing cold air?
A short burst of cool air doesn’t always mean your heat is broken. It can happen during startup, between heating cycles or while a heat pump defrosts. If the air stays cold and the room temperature keeps falling, start with these checks.
Start with three simple checks
- Check the thermostat. Select Heat and set the temperature above the current room temperature.
- Check the fan setting. Fan On can keep air moving between heating cycles, when the system isn’t producing heat. Use Auto unless your system needs a different setting for ventilation.
- Check the filter and vents. Replace a dirty filter and clear anything blocking supply vents or return grilles. Our air filter guide explains how to choose a suitable replacement.
After those checks, watch the room temperature. Whether the house is warming up tells you more than how one vent feels against your hand.
Do you have a furnace or a heat pump?
The next step depends on what heats your home. A gas furnace burns natural gas or propane. An electric furnace uses heating elements. A heat pump moves heat indoors and also provides cooling in summer.
Some homes combine a heat pump with a furnace or electric backup heat. If you aren’t sure which setup you have, a previous service report may identify it. You can also ask us to help.
Why would a furnace keep blowing cold air?
Cool air can briefly move through the vents before the furnace warms up. If a gas furnace never produces warm air, its ignition system or a control may need attention.
Restricted airflow can also make a furnace overheat. A safety control may stop the burners while the fan continues running. If the thermostat, filter and vent checks don’t solve the problem, arrange service. Leave burner, wiring and safety-control repairs to a technician, and don’t repeatedly reset a system that keeps shutting down.
What’s normal for a heat pump?
A working heat pump often delivers air that feels less hot than furnace air. If the rooms are reaching the set temperature, that difference alone doesn’t indicate a problem.
In cold, damp weather, the outdoor coil can collect frost. The system briefly enters a defrost cycle to clear it. You may notice steam outside, a stopped outdoor fan or cooler air indoors. Normal heating should return afterward.
Thick ice that remains on the unit or keeps building is a reason to call. Don’t chip it off; that can damage the equipment.
What do AUX and Emergency Heat mean?
AUX means backup heat has come on automatically. That can happen in colder weather, during defrost or after a large thermostat adjustment. The message by itself doesn’t mean something has failed.
Emergency Heat is a separate setting. It generally stops heat-pump heating and uses the backup source instead. Follow your system’s instructions or your technician’s advice about when to use it.
If the message stays on more than usual, our auxiliary heat guide explains what to watch for and when to arrange service.
When does cold air need a repair visit?
Arrange heating repair if the house keeps getting colder, the system repeatedly shuts down or heavy outdoor ice doesn’t clear. When you request service, share the thermostat setting, room temperature and whether the cold air is constant or comes and goes. Haven serves Fort Mill and surrounding areas.
If you smell gas, leave immediately and call your gas utility or 911 from a safe location.