Why Is My Heat Pump Blowing Cold Air? What's Normal and What Isn't

If your heat pump seems to be blowing cold air this winter, it may be working exactly as designed. Heat pump air usually feels cooler than the hot blast from a gas furnace, and a defrost cycle can blow cool air for a few minutes. If the house isn't warming up, though, something needs attention.

Here's how to tell the difference, and what you can safely check before you call.

Why does heat pump air feel cooler than furnace air?

A gas furnace burns fuel and pushes out very hot air in short bursts. A heat pump moves heat from the outdoor air into your home, so the air from your vents is warm but not hot. It runs longer and steadier to keep the house at your set temperature.

Hold your hand to a vent and the air may feel close to body temperature. That's normal as long as the house is holding temperature.

What is a defrost cycle?

On cold, damp mornings, frost builds up on the outdoor coil. Your heat pump clears it by briefly switching into reverse. During that time you may see steam rising from the outdoor unit and feel cooler air inside. Most systems turn on backup heat during defrost to soften that, and the cycle ends on its own within a few minutes.

Frost that clears is normal. An outdoor unit that stays covered in thick ice is not.

What should I check first?

1. Thermostat mode. Make sure it's set to Heat, not Cool or Auto, and that the set temperature is above the room temperature.
2. Fan setting. If the fan is set to On, it keeps blowing air even between heating cycles, which feels cool. Set it to Auto.
3. Air filter. A clogged filter cuts airflow and makes the system struggle. Replace it if it's dirty.
4. Breakers. Your heat pump has an indoor unit and an outdoor unit, often on separate breakers. Check that neither one has tripped.
5. The outdoor unit. Clear away leaves, pine straw, and anything stacked against it. Never chip at ice with a tool.

When is cold air a real problem?

• The house keeps getting colder even though the system runs constantly.
• The outdoor unit is encased in ice for hours and doesn't clear.
• The outdoor fan isn't spinning while the system is running.
• You hear new noises, like grinding, banging, or loud clicking.
• It only blows cold air, even after the checks above.

These can point to a refrigerant leak, a failed reversing valve, a bad defrost control, or a problem with the backup heat strips. Those are repairs for a licensed technician.

Should I switch to emergency heat?

Only if the heat pump itself has stopped working and you need heat until a technician arrives. Emergency heat runs your backup heat alone, and it uses a lot more electricity. We explain the difference in aux heat vs. emergency heat.

When should I call a pro?

If you've checked the thermostat, filter, breakers, and outdoor unit and the house still isn't warming, call Aero Air Services at (888) 409-2376 or request service online. See our heat pump repair page for what a visit includes. We show up. We clean up. We back our work.

Frequently asked questions

Is it normal for a heat pump to run all the time in winter?

On cold days, long run times are normal. Heat pumps are built to run steadily. It's a concern if the house still can't reach the set temperature.

Why is there steam coming from my outdoor unit?

That's usually the defrost cycle melting frost off the coil. It should stop within a few minutes.

Can a heat pump keep up in a Georgia winter?

Yes, in most cases. Our winters are mild compared to the North, and backup heat covers the coldest mornings. If yours can't keep up on an average winter day, have it checked.