What Causes a Significant Power Drop When Turning on the Car Air Conditioning?
4 Answers
When the car's air conditioning is turned on, there is a noticeable power drop because the car's maximum power is around 100 kW, while its usual power output is only 20 kW to 30 kW. When the car is moving at a constant speed, suddenly turning on the air conditioning diverts some of the engine's power, making the car feel sluggish. The impact of turning on the air conditioning is particularly significant for small-displacement cars. The car's power output directly affects driving performance when the air conditioning is on. If the car's engine has higher power and displacement, the perceived power loss due to the air conditioning is less noticeable. Conversely, if the engine has lower power and displacement, the perceived resistance is greater. Tips for Using Car Air Conditioning: After starting the car, avoid turning on the air conditioning immediately. It is best to wait for a while before activating it. When the engine is cold, turning on the air conditioning increases the engine's load, which not only consumes more fuel but can also damage the engine. After turning on the air conditioning, it is advisable to open the windows immediately for ventilation before closing them. In summer, the temperature inside a closed car cabin can reach 60–70 degrees Celsius. High temperatures can cause interior materials to release toxic and harmful gases, so it is essential to ventilate the cabin before closing the windows and driving.
I've been driving for decades, and the power drop when using the AC is quite noticeable, mainly due to the engine's additional burden from the compressor's power demand. Once the compressor kicks in, it's like adding a task to the engine—energy originally used to drive the wheels now has to be shared for cooling, especially noticeable in small-displacement cars or when climbing hills. In summer, driving on the highway with the AC on feels like the car is dragging a tail when climbing, and the throttle response becomes sluggish. Don’t just blame the car’s age—over time, the AC system may lose efficiency, so it’s recommended to regularly check the refrigerant and belt tension to ensure smooth operation. If power is really lacking, turning off the AC for a dozen seconds can provide a temporary speed boost. This issue isn’t limited to small cars; even my old friends’ SUVs often complain about it—it’s essentially trading a bit of power for comfort.
When I turn on the AC in my small car, the power drops noticeably, making the car feel heavier and slower to accelerate. The AC compressor draws energy from the engine, which has to divert horsepower to power the cooling system. This difference is especially noticeable when starting from traffic lights in the city, and it's more severe in small-displacement cars because their total horsepower is limited—the AC can consume 10% to 20% of the engine's power. Don't worry, this is normal. Try avoiding using the AC when climbing steep hills or choose cooler times to use it. A dirty AC filter can also worsen the issue, so I make sure to replace mine every six months. Proper maintenance can reduce the sluggishness but won't eliminate it completely, as the engine's power is simply limited.
The key to power loss when the air conditioning is on lies in the compressor operation increasing the engine load. The compressor, driven by the engine belt, consumes horsepower, which takes away the power normally used to drive the wheels, resulting in reduced output. This is how the car's structure works—when the compressor is activated, the engine has to multitask. From my experience, smaller displacement cars are more prone to slower throttle response and even a slight increase in fuel consumption, but it's not a big issue. For prevention, it's recommended to check that the refrigerant is sufficient and the compressor is functioning efficiently to avoid worsening the situation. On hot days, the power loss from using the air conditioning is more noticeable and can sometimes affect acceleration safety.
