An air conditioner or heat pump’s compressor creates the cooling capacity for the system and can come in single-stage, two-stage or variable-speed options. Each of these compressors offers the ability to run 100% capacity when demand requires it.

Single-stage: Traditionally, base model compressors are single-stage, which means the compressor runs full ON or OFF. With these models, your cooling system turns ON at 100% capacity and then OFF until your thermostat or control system reach the temperature setting you have selected.

For example: if your single-stage unit has a 3-ton capacity (measured in capacity, not weight), it will use all 3-ton or 100% capacity to cool your indoor space. The unit cycle ON and OFF as many times as necessary to meet your indoor temperature request!

Two-Stage: Two-stage compressor offer two capacity options. It’s like having two units built into one — a low capacity one to handle a smaller demand and a larger one to meet heavier demands.  If condition exist that 100% capacity is not required, a two-stage compressor can operate at lower speed, offering part-capacity to reach your desire indoor temperature.

While may mean that your unit’s ON cycle time will be lengthened, the power needed to support the lower speed would be reduced compared to a simple, single-speed system.

Variable-speed: Variable-speed compressor technology allows the unit to run at the speed the best meets your comfort needs coupled with energy-efficient operation. A variable -speed air conditioner or heat pump is designed and engineered specifically to provide the output needed at the lowest consumption of power.

Just like a car’s various gears, variable speed compressors can operate at various levels of the output depending on the conditions. Systems with variable-speed technology may run at the full capacity on hot summer days or reduced capacity for milder days. It is a great energy-efficient option when compared to the single-speed unit.

Once the indoor temperature you set on the thermostat or control system is achieved, the variable-speed unit will strive to operate at the lowest speed possible to deliver consistent, energy-efficient comfort into your home.


Because a variable-speed air conditioner or heat pump can adjust capacity for demand, it may longer than a single-stage unit under the same conditions. However, as the Department of Energy suggests, operating the compressor at the lower speeds for a longer duration may reduce the total energy consumption required to cool your indoor spaces of your home without a loss of the unit’s ability to cool your home.


What is the difference between a single-stage and a two-stage air conditioner?

The main difference between the two-stage of ACs is the type of compressor they use (the part of the AC that compressor the refrigerant)

A single-stage air conditioner’s compressor only works one level of operation—cooling your home at full blast.

A two-stage air conditioner’s compressor works at two levels of operations:

1) High for hot summer days (the equivalent of full blast for single-stage ACs)

2) Low for milder days when you don’t need as much cooling


What are the benefits of getting the tow-stage over the single-stage air conditioner?

The two main benefits of getting the two-stage air conditioner are:

1) Greater energy efficiency (meaning lower energy bill)

2) Greater comfort

Let’s explain why.

Greater energy efficiency

Like a car, an air conditioner coast less to operate when it turns on and of less often. Each time the AC start up, it cost more because of the energy needed to star up.

A single-stage air conditioner turns on and off more frequently because it can only cool at one speed, the turns off once it reaches thermostat setting.

But the two-stage air conditioner can meet your cooling needs about 80% of the time with its low setting, meaning it will run more often without as many starts and stops.

Greater comfort

Because the two-stage air conditioner runs more often, it will provide more even cooling and can remove twice as much moisture/humidity from your air.