After switching off the engine of a vehicle, it is generally recommended to keep the air conditioner (AC) running for a minute or two before turning it off completely. This practice allows the AC system to properly shut down and helps prevent potential issues. Here's why:
Compressor protection: The AC compressor operates using engine power. When you turn off the engine, the compressor continues to run for a short time, drawing power from the battery. Keeping the AC running for a minute or two after the engine is shut off allows the compressor to complete its cycle and equalizes pressure within the system. This helps prevent strain on the compressor and potential damage.
Condensation drainage: The AC system removes moisture from the air inside the vehicle, and this moisture can condense on the evaporator coils. Allowing the AC to run for a short time after turning off the engine enables the system to evacuate any condensation properly. It helps prevent the growth of mold or mildew and reduces the likelihood of foul odors inside the vehicle.
Preventing heat buildup: After parking the car, especially on hot days, the interior can become quite warm. Running the AC for a brief period helps reduce the heat buildup and keeps the cabin more comfortable when you return to the vehicle later.
It's worth noting that some modern vehicles have an automatic feature that runs the blower fan and AC system for a short time after the engine is turned off. This feature is often referred to as "afterblow" or "after-run," and it serves the same purpose as mentioned above.
However, if your vehicle does not have this automatic feature, it's a good practice to manually run the AC for a minute or two before turning it off when you park the car, especially during hot weather conditions.