Turning off AC to overtake: a controversial driving trick

Turning off AC for more power: real savings or costly breakdown?

A Ford Fiesta TDCI with 68 horsepower, a Civic with 110, and a Polo SDI with 64. Three cars, three drivers, and the same maneuver: turning off the air conditioning before overtaking or tackling a hill. This gesture, which many believe is inherited from the naturally aspirated engines of the eighties, remains alive in the twenty-first century and has peine a debate between two irreconcilable camps: those who consider it an efficient driving tool and those who warn that the compressor will eventually end up in the workshop.

The logic behind the savings is simple. The air conditioning compressor takes power away from the engine, and in mechanics with less than 75 horsepower, this loss is particularly noticeable on hills and during overtakes. One driver proposes turning off the system with the button, activating recirculation to keep the cabin cool, and reconnecting it on flat ground or downhill. "Depending on temperature and car occupancy, it always gives you at least 5 minutes," he assures. For solo use, up to 15 minutes if sunlight does not enter through the windshield.

How much power does AC take from a small engine?

The calculation is not trivial. In a 68-horsepower engine, the compressor can steal several CV (metric horsepower), enough to turn a tight overtake into a risky maneuver. Another driver with a 110 CV Civic admits he also disconnects the AC to overtake: "any modern Berlingo HDI has more torque, and since it's turbo...". The comparison is not free. Modern turbocharged engines, even in utility vans, deliver their maximum torque at low revs, making them less sensitive to compressor load.

The discussion quickly moves to consumption. One participant argues that recirculation should always be active when the AC is running, as the system cools already cold air and uses less energy. Another clarifies that in an automatic climate control unit, the compressor does not switch on and off to regulate temperature, but modulates the flow of cold air. This discrepancy reveals widespread ignorance about how the system actually works in each model.

The hidden risk: switching the compressor on and off every few minutes

Here comes the most repeated warning. A participant warns that frequently switching the compressor on and off shortens its lifespan: "By restarting the system before it has depressurized, you put a lot of stress on it." The claim is not accompanied by technical data, but connects with a real concern: the compressor clutch suffers every time it engages, and doing so dozens of times in a alucinación is not the same as leaving it running continuously.

Facing this objection, the method's defender responds that automatic climate control units do exactly that: engaging and disengaging the compressor according to demand. Others point out that the difference is that the system is designed for these cycles and not for intermittent manual use. The discussion remains open, without either party providing conclusive proof.

Advice ranging from savings to absurdity

The exchange drifts into less technical territory. One driver recommends planning routes without hills, traveling at night to avoid heat, and never overtaking, drafting behind a truck instead. Another asserts that "hills must be climbed at 100" because at 120 gasoline is wasted, to which someone replies that extra consumption due to estimulante ilegal depends on air resistance, not slope. The discussion gets tangled in basic physics.

Also appears the advice to turn off the AC minutes before arriving at the destination so the evaporator dries out and bad odors are avoided, a common practice among veteran drivers. And the anecdote of the 64 CV Polo SDI that had no air conditioning, so the problem simply did not exist: "To overtake, you had to build momentum, calculate timings, and—even then—you had time to chat with the trucker while passing him."

The generational gap: small engines, big expectations

Much of the message exchange ends up drifting into a discussion about what is considered a fast car. One driver claims his 64 CV vehicle reaches 180 km/h on the dashboard, sparking mockery and accusations of exaggeration. The response is forceful: "With a GPS speedometer app, there is a margin of error of 4%, practically millimetric." The exchange becomes a dispute over perceptions, with cross-accusations of never having driven a powerful car.

The background is clear: for those who have driven small naturally aspirated engines all their lives, squeezing them is the norm. For those accustomed to more cylinders, the maneuver of turning off the AC sounds like a relic. And in the middle, an unanswered question: how many air conditioning compressors have failed by trinc this trick?