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.