variable speed vs regular units
Deciding on what kind of unit to get is very important when looking for a new air conditioner, there are single stage, two stage and variable speed units. The components are important because they affect the overall efficiency of the system. There are compressors for regular units that can be single or two stage and units that have variable speed. The blower motors can also operate at different speeds and efficiencies. The difference of the units is huge for initial investment and the benefits of having them in the long run. Basically, variable speed will be more expensive initially but its high energy efficiency will save you more money in the long run. They work great for the Arizona climate because when it cools down they won’t operate at full power while the single stage units will still be working like it’s 115 outside! Below we’ll give you a breakdown of their components and help you decide what’s best for you.


SEER stands for seasonal energy efficiency ratio and will tell you how efficient your air conditioner is. It is a measurement of BTU’s produced over electrical energy consumed in a given season. The higher the rating the better the system is at using the energy it consumes and converting it to actually cooling the home.

Unit TypeSeer Ratings
Single Stage14-15
Two Stage16-18
Variable Speed 19-22
hvac compressor


The compressor is used to compress Freon to increase pressure. They can operate as single stage, two stage, or variable speed. It’s a very important part of the refrigerant cycle because it’s necessary to maintain the pressure/temperature differential of the refrigerant. The more efficient this part is the more efficient your unit will also be.

Single Stage

Used on low end equipment these compressors only can turn on to full power then off.

Two Stage

High and low operating speeds. Depending on conditions this motor can operate at high speed for the hotter time of the year and at a lower speed when it cools down.

Variable Speed

Can work at whatever speed is necessary to cool or heat home. Works from 0% to 100% it will account for whatever conditions there are so that it can cool or heat your home with the least amount of energy possible.

How Compressors Work
hvac blower motor

Blower Motors

Blower motors are necessary to deliver the heated or cooled air into your home to satisfy the thermostat. They are a vital part of the duct system and to system efficiency. Their efficiency depends on how much energy they consume that is used and the condition of your ductwork because if it’s in bad shape then your motor will have to run more than normal to satisfy the thermostat.

Single Stage Units

Single stage units use PSC motors that only operate at one speed and only convert about 60% of the energy it uses to actually motorize the blower. They are simple in design, easy to make, and are used on inexpensive units. They only operate at one speed and can not maintain a constant torque. They use capacitors and alternating current and are best for low end units.

Two Stage Units

Two stage units use the X13 motor and its made to deliver a constant torque. Torque is the twisting force of the motor so it will adjust speed to what is necessary to maintain that torque. It’s better than the PSC because it uses less energy and can maintain its torque. They are similar in design to variable speed motors and are used on mid range equipment.

Variable Speed Units

ECM motors are variable speed motors that adjust their speed to whatever is necessary to satisfy your thermostat with the least amount of energy usage. This allows for the constant airflow that’s required to keep your home at desired conditions. They use about 80% – 90% of the energy they consume to motorize. They have a brushless design, direct current and are used on high end equipment like variable speed units.

programmable thermostat


There are variable speed units that can use a programmable thermostat along with zone dampers to deliver the most comfort at maximum efficiency. Its called zoning and only variable speed units with communicating capability can do this. You can control the temperature of individual rooms and “areas” from a main programmable smart thermostat.

Variable Speed Is Superior

After considering the efficiency of the air conditioners and their components the variable speed units are superior. They are more expensive initially but provide long term benefits that save money. If you ever want to zone your homes air conditioning system variable speed will be necessary and will deliver the most efficient comfort you can get. If you’re on a low budget then opting for the lower end equipment might make sense especially with the mid range equipment still offering good efficiency.

If you’re in Phoenix you can contact us today for a free quote.