Skip to main content

When driving your car in the summer, you probably don’t think too much about anything other than a cooler cabin when you hit the “AC” button on your dashboard. After all, as long as cold air comes out of the vents, it doesn’t really matter what your car’s air conditioning system is doing, right?

Well, turning on your car’s AC can actually affect fuel economy slightly. But it can also affect your car’s horsepower output. But how much power does AC really pull from the engine?

Your car’s AC system is powered by the engine

A car air conditioning control panel
Car Air Conditioning | Michal Fludra/NurPhoto via Getty Images

Without getting too technical, your car’s air conditioning system has multiple parts and is connected to the engine via a drive belt that runs the alternator and water pump as well. When the AC system kicks on, you might notice that the engine RPM increases a little. According to Your Mechanic, the car does this in order to offset the power drawn by the AC system, so there’s no doubt that the system robs your engine of horsepower when it’s activated.

How much horsepower does a car lose with the AC on?

That’s pretty much the age-old question since the amount of power an engine loses can vary depending on what type of car you drive. Smaller engines might not lose as much power, while larger engines can lose more since the power loss is a percentage of the overall horsepower output.

According to actual testing done by a YouTuber named “Sikky,” the average amount of power and torque that’s lost to the drive wheels is around 10 each, across the board. The YouTuber strapped a Lexus IS-F to a Dynapack dynamometer, which measures the horsepower at the car’s hubs.

According to his testing, the Lexus IS-F produced 363 hp with the AC on and it jumped up to 372 when the AC was turned off. And while that power loss could be relevant to that specific car — especially since it has a large V8 engine – we can assume that you’ll find the same type of power loss on most cars that you’ll drive.

Minimizing your car’s power loss due to the AC system

If you want to ensure that you’re maximizing your car’s full power potential, but still want the luxury of having AC, then you can use some of these simple practices:

  • Only use your car’s air conditioning system when needed. There’s an “on/off” button, after all.
  • If your car is equipped with automatic climate control, then you can set the interior temperature to the same as the outside temperature. Doing so will ensure that the AC system doesn’t activate as frequently.
  • Make sure that the air conditioning system is switched off when you start the car. It won’t make a huge difference, but it can still save your engine some power.

The next time you turn your car’s air conditioning system on, you’ll likely notice the loss of power. Although it’s not enough of a loss to prevent you from driving up a hill, it’s still noticeable. Fortunately, there are ways to circumvent the power loss, even if it is only 10 horsepower.


What to Do If Your Car AC Stops Working