Is a Variable‑Speed Air Conditioner Worth the Cost in Phoenix?

Updated April 2024

If you can swing the high upfront cost, then yes, most AZ homeowners will find that variable-speed technology is “worth it” when compared to single-stage/single-speed ACs.

Note: The term “variable-speed” can refer to two different components in your AC: the compressor and/or the blower motor. If you’re looking at an AC that’s labeled “variable-speed”, be sure to ask a licensed technician or manufacturer which component(s) has “variable-speed technology”.

In this post, we’ll cover:

Note: To be clear, the terms “single-stage” and “two-stage” refer to AC compressors, while “single-speed” and “multi-speed” refer to blower motors.

Think of single-stage/single-speed units as operating like a basic light switch: they work at one level—HIGH, which means when they’re on, they’re going full blast at 100% capacity.

Variable-speed technology works more like a dimmer switch: they can adjust to any operating capacity needed. In fact, variable-speed units can operate anywhere between 10% and 150% capacity, making them much more efficient at keeping Arizona homes cool in the summer.

For example:

Imagine a scorching 115° July day here in Phoenix. Let’s look at how a single-speed/single-stage unit would handle the extreme temperature versus a variable-speed unit:

• Single-speed/single-stage AC: Turns on at full-blast, cools down your home quickly and then shuts off. These short ON/OFF cycles repeat continuously, resulting in hot/cold spots in your home and inconsistent indoor temperatures.
• Variable-speed AC: Initially blasts at 150% to cool the home quickly but then automatically ramps down to 30-40% capacity once the indoor temperature is close to the desired temperature. At 30-40% capacity, the AC provides a slow and steady stream of cool air. This results in even cooling throughout the entire home and indoor temperatures that precisely match the set temperature.

To help you visualize the difference in performance, the chart below shows a home when it’s at a set temperature.

• The yellow line shows how a single-stage/single-speed unit runs at 100% until your home reaches the set temperature. Then the AC shuts off until indoor temperatures rise to a few degrees warmer than the set temperature, then it turns back on.
• A variable-speed unit (the grey line in the graphic) runs longer but at a lower capacity—maybe between 30% and 50% to maintain the set temperature.

• More comfort. A variable-speed AC’s longer run times and lower speeds means cool air is steadily pushed throughout the whole house to provide even temperatures. Longer run times also allow for better dehumidification.
• Lower electric bills. The ability to ramp down in speed means that your AC uses only the lowest amount of electricity needed, meaning lower energy bills throughout the year.
• Quieter operation. Since variable-speed blowers can operate at any capacity (not 100% all the time), they have lower decibel levels than other AC units.
• Qualifies for rebates. In Arizona, you could get up to $800 from SRP for installing a unit with a variable-speed compressor.

The cost to install a variable-speed AC unit is about $4,000–$8,000 more than other units. The total cost of a variable-speed AC installation is usually around $17,000 to $26,000.

But variable-speed technology isn’t the only factor that can raise the upfront cost. In fact, the overall cost of an AC installation varies depending on many factors, including:

• The size of your unit
• The efficiency you choose (SEER rating)
• Features you add (like noise reduction or air quality features)
• The contractor your choose

If you can’t swing the high upfront cost of a variable-speed AC but want more comfort than a single-stage/single-speed unit, consider one of the mid-range unit options below:

• Two-stage: If an AC is a “two-stage” unit, it means that the compressor—the part in the outdoor unit that pumps refrigerant through your system—has two operating capacities (high and low).
• Multi-speed: If an AC is a “multi-speed” unit, it means that the blower—the part in your indoor unit that blows cool air throughout your home—has up to five preset speeds (like a ceiling fan).

Let’s look at how two-stage and multi-speed units compare to variable-speed technology:

As you can see, a two-stage/multi-speed unit (red line) still doesn’t provide as precise temperatures as a variable-speed unit (grey line).

But, remember the wildly fluctuating yellow line of single-stage/single-speed units in the earlier graphic? Compared to that, two-stage/multi-speed units provide longer run times and more precise temperatures.