What Is a 2-Stage Air Conditioner?

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Updated September 9, 2022

When considering the best air conditioners for your home, energy efficiency and cooling capacity are crucial considerations, just like what a good SEER rating is for air conditioners. Often, homeowners are forced to buy a unit without adequate cooling power because of its good efficiency. This is why two-stage AC units are a worthwhile investment. And if that leaves you wondering, “What is a 2-stage air conditioner?” stick around to learn more.


  • The two-stage compressor allows the unit to operate at two speeds, high and low, depending on the temperature shift needed.
  • The main benefit of a two-stage unit is that it significantly decreases energy bills.
  • Two-stage systems also increase indoor comfort through more seamless humidity and temperature control.

Defining a 2 Stage Air Conditioner

Single-stage ACs are the most common form of AC unit, meaning they operate on one power setting. So, when the AC is on, the single-stage air conditioners run at full power, and when they’re off, they’re completely off. This differs a bit from a 2-stage unit.

Insider Tip

The best way to estimate energy savings on air conditioners is to compare the seasonal energy efficiency ratio (SEER rating).

How a 2-Stage Air Conditioner Works

The two-stage air conditioner works similarly to a 1-stage unit but incorporates a compressor, which allows the AC unit to operate at two speeds. The low setting works at a slower speed and kicks in for temperature changes of less than 5 degrees, and the unit will employ the higher speed to deal with more dramatic temperature shifts.

If you’d like to learn about options aside from one- and two-stage air conditioners, read our article explaining what a package air conditioner is.

Benefits of a Two-Stage Air Conditioner

Two-stage systems provide significant energy savings. The lower setting operates at around 40% less power than the high setting. In addition, two-stage systems work on the low stage nearly 80% of the time, resulting in hundreds in savings every year.


Because two-stage AC systems require a significant investment, it’s often unwise to purchase one if you don’t plan on living somewhere for only a short span.

Beyond efficient operation, there are also comfort benefits. For example, the lower setting provides a more subtle cooling effect, and smoother temperature fluctuations reduce the likelihood of becoming chilled or reaching uncomfortable humidity levels.

STAT: Power settings vary by manufacturer, but the lower setting of two-stage systems typically operates at 60-80% of the total power of the high setting. (source)

Although the two-stage unit drastically decreases energy consumption, single-stage system owners can learn how to make an air conditioner more energy efficient. One such way to do this is by understanding what the dry setting on an air conditioner means and when to use it.

What Is a 2 Stage Air Conditioner FAQs

How long do two-stage AC systems last?

Two-stage systems typically last over 20 years because they are made with higher quality parts and more precision manufacturing. The variable speeds also put much less strain on the motor.

How much do two-stage AC systems cost?

Two-stage central air conditioners typically cost between $4,000-$5,000. They also tend to cost more to repair.

What are variable speed air conditioners?

Variable speed air conditioners have multiple levels of operation when it comes to cooling stages. Some variable systems have up to hundreds of settings.
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