How Your Subaru’s Air Conditioning System Works

June 29th, 2026 by

 

 

Photo Credit: Subaru

Does Using the AC Use Gas?

When it comes to driving in hot weather, many drivers wonder: does using the AC use gas? The short answer is yes; running the air conditioning in your Subaru vehicle does consume gasoline. Because the AC system relies on the vehicle’s engine to power its key components, turning it on places an extra load on the engine, which naturally requires more fuel. Fortunately, modern Subaru Boxer engines are highly optimized for efficiency, meaning the drop in your miles per gallon (MPG) is relatively small compared to older vehicle models.

How Your Subaru’s Air Conditioning System Works

To understand why this happens, it helps to know how a car’s climate control system operates. Your Subaru’s air conditioner functions like a miniature refrigerator, moving heat out of the cabin using a closed-loop system:

  • The Compressor: This is the heart of the system. It is driven by a serpentine belt connected directly to your Subaru’s engine. When you turn the AC on, the engine must work harder to turn this compressor.
  • Refrigerant Expansion: The compressor pumps refrigerant through a condenser and an expansion valve, turning it into a cold gas that absorbs heat from inside the car.
  • The Blower Motor: An electrical fan blows air across the freezing cold evaporator coils, pushing refreshing, chilled air out of your dashboard vents.

Is Using Car AC Fuel-Efficient?

While the system does draw power, using your car’s AC can actually be fuel-efficient depending on your driving environment. In stop-and-go city traffic, the extra strain on the engine is at its highest, making the AC less efficient than opening your windows. However, when you are cruising at highway speeds, opening the windows creates immense aerodynamic drag. This drag forces your engine to work much harder to push through the air than it would to simply run the climate control. Therefore, at speeds above 45 MPH, using the AC is actually the more fuel-efficient choice.

Other Ways to Improve Your Fuel Economy

Beyond managing your climate control, there are several other practical ways to improve your Subaru’s overall fuel economy during the warmer months:

  • Utilize AC Recirculation: Once the initial blast of hot air escapes your cabin, switch your AC to “recirculate” mode. This cools the air already inside the vehicle rather than pulling in hot air from the outside, easing the workload on the compressor.
  • Check Tire Pressure: Under-inflated tires increase rolling resistance, which forces your engine to burn more gas.
  • Lighten the Load: Remove unnecessary heavy gear, roof baskets, or cargo carriers when you aren’t using them to reduce both weight and aerodynamic drag.
  • Keep Up with Maintenance: Clean engine air filters, fresh motor oil, and new cabin air filters allow your Subaru to run at peak thermodynamic efficiency.

Maximize Efficiency

If you want to ensure your vehicle is operating at its absolute best, the team at Southern Team Subaru is here to help. Regular maintenance—such as checking your refrigerant levels and servicing your engine—is the best way to answer the question “does using the AC use gas” with the highest MPG possible. Stop by our service center today to keep your Subaru running efficiently all season long.

Posted in Subaru