What does REST mean in a car?
3 Answers
REST in a car refers to the residual heat heating function, which 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, before automatically shutting down. The REST button function is particularly useful during short winter stops when the engine is turned off, as it helps maintain the interior temperature, preventing rapid cooling. This eliminates the need to restart the air conditioning system to reheat the cabin when the vehicle is started again. To activate it, simply press the "REST" residual heat control button on the center console after turning off the engine. When using the air conditioning in winter, note the following: Do not immediately turn on the warm air when starting a cold engine. Since the engine has just started, the radiator temperature is still 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 its normal temperature rise. First, warm up the engine, and only after the engine temperature gauge reaches the midpoint should you turn on the heater. At the same time, set the air circulation to external mode to allow cold air inside the car to be expelled. After 2-3 minutes, you can switch the air circulation to internal mode. Besides using the air conditioning for heating, you can also utilize the engine radiator's water temperature to provide warmth. This method does not require the compressor to be turned on, resulting in significantly lower fuel consumption compared to using the air conditioning. After prolonged use of the car's air conditioning and heating, many people feel warm but often experience discomfort in breathing. This is because the car is an enclosed space, and continuous heat exchange during breathing can make the air feel stagnant. To alleviate this, you can slightly open a crack in the windows to release some of the hot air, reducing the sensation of chest tightness caused by prolonged heating. Correct usage method: If you need to temporarily park the vehicle and want to maintain the interior temperature, press the REST button on the car's air conditioning system before turning off the engine. When you press the REST button on the car's air conditioning, the indicator light next to the button will illuminate, confirming successful activation. Simply set the desired temperature for the air conditioning. The REST function will maintain the temperature for up to 30 minutes, provided the car battery has sufficient charge. To stop the function, press the REST button again. If the battery charge becomes insufficient while the REST function is active, potentially affecting the vehicle's normal startup, the REST function will automatically shut off to ensure the car can start properly.
Last winter, I encountered this situation when taking my kid to class. After turning off the car while waiting for my child to finish school, I started feeling chilly within just five minutes of shutting off the engine. That's when the REST button on the dashboard came in handy—pressing it allowed the vents to continue blowing warm air for another half hour. It works by utilizing residual heat from the engine, consuming no extra fuel or electricity, making it perfect for short stops while waiting. Just remember to use it while the engine is still warm; if the car has completely cooled down, it won't be effective. This feature has become essential for me during winter school runs—it's much more convenient than restarting the engine just to warm up.
Last winter, my buddy and I were driving back from skiing when we stopped at a service station for a break and discovered a practical feature. After parking and turning off the engine, I pressed the REST button on the air conditioning panel, and hot air actually continued to blow from the vents. The car's manual stated that this was the residual heat heating function, which utilizes the warmth from the recently stopped engine to provide heating for an additional 15-20 minutes. In practice, it was enough time to finish a cup of instant noodles before hitting the road again, and it saved much more fuel than idling with the air conditioning on. This feature is commonly found in German cars, and it's important to note that it only works when the temperature gauge is still in the middle range.
