What does REST on the air conditioner mean?
2 Answers
REST on the air conditioner refers to the residual heat function. This feature utilizes the engine's residual heat to continue providing warm air inside the vehicle for up to half an hour after the engine is turned off, after which it automatically shuts down. The REST button function is particularly suitable for short-term parking and engine shutdown in winter, as it helps maintain the interior temperature, preventing it from dropping rapidly. When restarting the vehicle, there is no need to turn on the air conditioning system to reheat the interior. To activate it, simply press the "REST" residual heat control button on the central console after turning off the engine. Do not immediately turn on the warm air when starting a cold engine. Since the engine has just started, the radiator temperature is very low in winter. Turning on the air conditioning will not quickly raise the car's temperature but will instead increase the engine's load and delay the normal rise in engine temperature. The engine should be warmed up first, and the heater should only be turned on after the engine temperature gauge reaches the midpoint. At the same time, set the air circulation to external circulation to allow the cold air inside the car to be expelled. After waiting for 2-3 minutes, the air circulation can then be set to internal circulation.
When I first bought my car, I was also curious about the REST button on the air conditioning. Later, I figured out that it utilizes the residual heat from the engine. After parking and turning off the engine, if you press the REST button, the air conditioning fan will blow warm air using the remaining heat from the engine, maintaining a comfortable temperature inside the car for about ten minutes. I often use it in winter when refueling or running to the supermarket to keep the interior cozy. It’s much more fuel-efficient than restarting the engine and also reduces emissions. However, note that the engine needs to be sufficiently warm for it to work effectively—performance is poor in summer or when the engine is cold. Occasionally, people mistake it for a malfunction, but it’s actually a clever design. In short, REST is a thoughtful and energy-saving little helper.
