Turn off the AC before shutting down the engine or shut down directly?

[EleanorLee]

Turn off the AC before shutting down the engine. Here are the relevant explanations: 1. Correct practice: For automotive design, directly shutting down the engine is not the correct practice. Just like it's best to close open programs before turning off a computer. Therefore, turning off the interior lights, wipers, music players, AC, etc. before shutting down the engine is the correct approach. 2. Mold growth: Not turning off the AC before shutting down the engine basically does no harm to the engine. However, there's another issue that cannot be ignored: In the AC ducts, the previously cooled air will remain stagnant due to the sudden cessation of air exchange, leading to the growth of a large amount of mold over time.

[HeidiRose]

Before parking each time, I always remember to turn off the air conditioning before shutting down the engine. This helps avoid putting extra strain on the engine during the next startup, especially during hot summer weather when direct activation of the AC compressor might make the car struggle. I recall once when I was in a hurry and forgot to turn off the AC, the battery almost couldn't handle the next startup. Since then, I've developed a habit of turning off the AC one or two minutes before reaching my destination, also reducing the fan speed to allow a natural temperature transition. This not only protects the electrical system but also extends component lifespan, preventing premature aging of parts like the compressor and battery due to voltage fluctuations. Spending a few extra seconds can save a lot of trouble and make the driving experience smoother and more comfortable.

[WalkerFitz]

From an energy-saving perspective, I always turn off the air conditioning before shutting down the engine. Directly turning off the engine keeps the system in a dormant state, causing a sudden surge in air conditioning load during the next startup, which quietly increases fuel consumption. I've done the math—over time, this can save a significant amount on fuel costs, plus it reduces component wear and lowers maintenance expenses. This principle also applies to using the heater in winter; turning off the fan and air conditioning in advance stabilizes the voltage, making the next drive smoother. Protecting your vehicle means protecting your wallet—this simple habit can bring long-term benefits. I recommend gradually lowering the fan speed before parking and shutting off the engine last to avoid unnecessary costs.

[Shaun]

My experience is to turn off the air conditioning before shutting down the engine. Because directly turning off the engine may leave residual power in the air conditioning system, which could cause engine shuddering or delayed startup. I make it a habit to immediately press the AC off button after parking, and also turn off the fan, which keeps the system cleaner. Especially during short commutes, this can prevent minor malfunctions. Fellow car enthusiasts have shared similar experiences - developing this routine makes car usage more reassuring.