Should the AC and Recirculation Be Turned On When Using the Heater?
4 Answers
You don't need to turn on the AC when using the heater. The AC button is used for air conditioning adjustment. In summer, when you turn on the cold air, you can press the AC button to activate the air conditioning compressor for cooling. In winter, when using the heater, there's no need to press this button. The AC won't engage the compressor for heating, as the heater doesn't rely on the compressor to generate heat. Instead, it transfers the engine's heat to the interior of the car. Using the heater doesn't consume extra fuel: The reason the heater doesn't consume extra fuel is that it transfers the heat generated by the engine into the car. Even if you don't use the heater, the engine still produces heat, which is then expelled outside the vehicle. Therefore, using the heater has no impact on fuel consumption. Precautions when using the heater: Since the heat from the heater comes from the engine, prolonged use can produce toxic gases like carbon monoxide, which can be dangerous for passengers inside the car. If you notice any unusual air quality inside the car, immediately open the windows or doors to ventilate and expel the toxic gases. Additionally, when there is frost or fog on the car windows, you can also use the heater to remove it.
You actually don't need to press the AC button for heating! The warm air comes from the engine's heat and has nothing to do with the air conditioning compressor. Turning on AC just wastes fuel and puts extra load on the engine. As for recirculation mode: use it when you first get in the car and are shivering from cold - the heat builds up faster and temperature rises sharply. But after 10-20 minutes you should switch to fresh air mode, otherwise the cabin gets stuffy and windows fog up easily. I experienced this on a long drive - keeping recirculation on too long made me feel dizzy, and I only recovered after opening windows at a service area. This is especially important in humid southern regions, or your windshield will fog up in minutes like it's covered with white gauze.
Here's how I operate the heater in winter: turn on the fan as soon as the temperature gauge needle starts moving, but don't rush to activate the AC. As experienced drivers know, running the AC compressor increases fuel consumption by about 10%. I usually only use the recirculation button during traffic jams to prevent exhaust fumes from entering the cabin. On highways, always maintain fresh air circulation - last time my sister got drowsy while driving because she kept recirculation on too long, causing oxygen deprivation. By the way, here's an easily overlooked tip: when using fresh air mode, remember to direct the airflow towards your feet since heat rises, warming your entire body. If you notice window fogging on rainy days, just turn on the AC temporarily for about a minute - no need to keep it running continuously.
There's really no need to press the AC button when turning on the heater. The fundamental principle of car heating is to blow the heat from the engine coolant into the cabin, and the compressor is not involved at all. However, there are three points worth noting: First, new energy vehicle owners need to turn on the AC when using the heater because there is no waste heat from the engine; second, in northern regions where temperatures drop to minus twenty degrees Celsius, remember to turn on the external air circulation, otherwise, the moisture from breathing inside the car can cause the windshield to freeze; third, for electric vehicles like Tesla, displaying the air conditioning icon on the screen when the heater is on is a normal energy conversion process and does not mean the traditional air conditioning is activated. During long-distance driving, I regularly switch between internal and external air circulation, and I pay extra attention to ventilating every half hour when traveling with elderly or children.
