Heat pump blowing cold air in winter? What is normal and what is not

Heat pumps are common around the Lake of the Ozarks and in Jefferson City, and a lot of winter calls about them start the same way: it's blowing cold air. Sometimes that's a real problem. Often it's the heat pump doing exactly what it was built to do.

Why heat pump air feels cooler than furnace air

A gas or propane furnace pushes out air that feels hot. A heat pump's air comes out warm, not hot, and if you hold your hand near the vent it can feel cool against your skin. If the house is holding the temperature on the thermostat, the system is working.

The defrost cycle

When it's cold and damp outside, frost builds up on the outdoor coil. Every so often the heat pump switches into defrost to melt it off. You may see steam rising from the outdoor unit, hear a whoosh when it switches, and feel cooler air at the vents for a few minutes. Then it goes back to heating. That's normal.

Signs it's a real problem

• The house keeps falling behind the thermostat, even on mild days.
• The outdoor unit is caked in thick ice that never clears.
• The outdoor fan isn't spinning, or the outdoor unit is silent while the indoor fan runs.
• The air is cold all the time, not just during short defrost periods.
• The thermostat shows backup or emergency heat running for much of the day.

What you can check yourself

The thermostat. Make sure it's set to heat, not cool or fan only, and set a few degrees above room temperature.

The filter. A clogged filter chokes airflow. Hold it up to a light. If you can't see through it, replace it.

The outdoor unit. Clear snow, leaves and anything piled against the sides, and keep about 2 feet of space around it. Don't chip ice off the coil with a tool. It's easy to puncture.

The breakers. Heat pumps usually have one breaker for the indoor unit and one for the outdoor unit. Check both.

Backup heat and your electric bill

Most heat pumps here have electric backup heat that kicks in on the coldest days and during defrost. It works, but it costs a lot more to run than the heat pump itself. If backup heat is carrying the house most of the day, something is usually off, like a refrigerant problem, a failed sensor or a defrost control that isn't doing its job. Those need a technician with gauges to sort out.

When to call

If those checks don't fix it, or the house can't keep up, call 24 Hour Heating and Cooling at (573) 693-8863. A real person answers 24/7, and you'll get a straight answer on timing. You can read more on our heat pump repair page.