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The Difference Between Single vs Variable Speed AC

Written by Comfort Solutions HVAC on . Posted in .

Purchasing a new air conditioning unit for your home can be a challenging process. There are many different brands, sizes, measurements, and technical jargon that you may need to learn to make an informed decision. It may be hard to determine which factors you need to pay attention to and what requirements your home may need. To make this process a little bit easier, here is a streamlined guide to help you understand the difference between single stage and variable speed air conditioners. 

How Does a Single Speed Air Conditioner Work?

 An easy way to explain how a single speed air conditioner works is by comparing it to a light switch; it is either off or on. When you use your thermostat to set your unit to your desired temperature, you are setting the point which will determine when the switch will be flipped. For example, if you set your thermostat at 74°F, any temperature that is above that point will turn your air conditioner on. Any temperature below that point and your air conditioner will turn off. During the time that it is on, it will run at a constant “single” speed. 

Single Speed Air Conditioners: Pros and Cons


  • Cheaper upfront costs
  • It is less expensive to install


  • Inefficient
  • Higher energy bills
  • Higher levels of wear and tear
  • It creates hot spots in the home
  • It provides less humidity control

How Does a Variable Speed Air Conditioner Work?

A variable speed air conditioner, as the name implies, runs at a variety of speeds instead of turning on and off between cycles. When more cooling is needed, the AC unit automatically adjusts to provide maximum power. Once the temperature on your thermostat is met, its speed can be reduced to as low as 25% of its maximum speed to provide efficient and constant cooling.  

Variable Speed Air Conditioners: Pros and Cons


  • Lower energy costs
  • Higher levels of efficient cooling
  • Improved humidity control
  • Fewer hot spots in the home
  • Lower levels of wear and tear from frequent on and off cycles


  • Higher initial costs
  • It may be costly to install
  • It requires specialized maintenance 

How is a Variable Speed Air Conditioner More Efficient If It’s Constantly Running?

It might sound counterintuitive that a variable speed air conditioner is more energy efficient than a model that spends a portion of its time completely turned off. However, there is an easy explanation. The majority of your air conditioner’s power use occurs when it is turned on, not when it is operating. This is because the compressor requires a large burst of energy to get started. Therefore, an AC unit that is continuously cycling between on and off consumes more electricity than a model that stays on for longer periods and reduces its speed as needed.

If you want to learn more about the benefits of a variable speed air conditioner and how its installation can save you money, our certified HVAC technicians at Comfort Solutions can answer any and all of your questions. 

For more information, please call us at 610-438-9300 or send us a message online to book your free in-home estimate.