Do you need to turn on the AC when using the car's cold air?
2 Answers
You need to turn on the AC when using the car's cold air; otherwise, the air conditioning system will only blow air at normal temperature. This is because the AC button controls the compressor, which is the main component of the cooling system. Keeping the air conditioning at a low temperature for a long time can create a large temperature difference between the inside and outside of the car, which may make you feel uncomfortable or even sick, and it will also increase fuel consumption. If you use the air conditioning for an extended period, it's advisable to open the windows to ensure good air quality inside the car. Additionally, before turning off the engine, you should turn off the air conditioning first to protect the compressor. While you need to turn on the AC for cold air, it's unnecessary to press the AC switch when using warm air, as the warm air simply transfers some of the heat originally dissipated by the radiator into the cabin.
To understand this, we need to start with the principles. The AC button in a car's air conditioning system is essentially the switch that controls the compressor, which is specifically responsible for cooling. So, should you turn it on when you want cold air? In most cases, yes, but it's not absolute. For example, during spring and autumn when the temperature is a cool 20 degrees Celsius, just opening the windows and turning on the fan for natural air can be quite comfortable—turning on the AC in this scenario would only waste fuel. On rainy days when the windshield fogs up, turning on the AC for cooling can quickly dehumidify the air, which is much more efficient than using hot air to defog. From my own decade of driving experience, I've found that after a car has been baking in the summer sun and the interior temperature reaches 40 degrees, you should first open the windows to ventilate before turning on the AC—this way, the car cools down faster.
