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Why Is My Air Conditioner Running During the Winter Season?

So you’ve turned on your heat and everything is running smoothly. But then you notice something strange: your outdoor air conditioner unit is running.

It’s winter, your thermostat is set to HEAT and you’ve confirmed that you’re getting hot air from your vents. So why the heck is your AC running?

Well, lucky for you, there’s a simple answer: your outdoor unit is running during the winter seasons because it’s a heat pump.

We’ll explain…

A heat pump runs in the summer and the winter

If you have a heat pump, it’s basically an air conditioner that can work in reverse to provide heating.

And the best part? Because you live in Arizona with mild winters, your heat pump saves you up to 50% in electricity usage compared to electric furnaces or baseboard heating.


Well, a heat pump moves heat instead of creating it (like a furnace does). Compared to electric furnaces, heat pumps use relatively little electricity to complete this “heat transfer” process.

During the summer, a heat pump uses refrigerant coils to absorb heat from inside your home and dump it outdoors. During the winter, that same unit can reverse the flow of refrigerant in order to absorb heat from the outdoor air and move it into your home.

For more information on how a heat pump differs from an air conditioner, check out our blog, “AC vs. Heat Pump: What’s the Best Cooling System for Phoenix Area Homes?”.

Note: You may also notice steam coming from your outdoor heat pump unit during the winter. But don’t be alarmed, this is normal. It’s just your heat pump going through a “defrost mode”.

Not 100% sure you really have a heat pump? Here’s how to tell…

Still not convinced that you have a heat pump? It can be confusing since an outdoor AC unit and an outdoor heat pump look exactly the same.

Two ways you can tell that you have a heat pump:

  1. Go outside and look for the model number on your condenser. Do a quick Google search and you should be able to discern whether you have an air conditioner or a heat pump.
  2. Look through the grill on the outdoor unit. If you see a brass contraption with 3 fittings on one side (called a reversing valve), you have a heat pump. This brass object is responsible for switching the unit from heating to cooling.

Don’t ignore a unit that runs year-round…

Now that you know your heat pump works non-stop throughout the year, you’ll want to be sure that you’re giving it the TLC it deserves.

We suggest getting your heat pump maintenance once before the cooling season and once before the heating season.

According to Energy.gov, you can lose 10% to 25% in energy savings if you don’t keep your heat pump well maintained.

Some common heat pump problems that maintenance can prevent include:

  • Low refrigerant
  • Heat pump stops switching properly to heating/cooling when it should
  • Higher electricity bills
  • Burnt out motors
  • Miscalibrated thermostats

Need heat pump maintenance in Phoenix?

Want to make sure your heat pump stays in tip-top shape? We can help you out.

Just schedule your heat pump maintenance with our team today. We offer a 100-point in-depth tune-up.

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