Does using car heater or air conditioning consume more fuel?
2 Answers
Using the air conditioning in a car consumes more fuel. While the heating system does not completely avoid fuel consumption, its usage is minimal and can generally be ignored. Heating Principle: Most car heating systems consist of a heater core connected to the engine's cooling circuit. The coolant, which absorbs heat from the engine, flows through this heater core. The heater core functions similarly to a water radiator, where the blower fan directs the heated air into the cabin to provide warmth. Therefore, the heating process does not consume additional engine energy but rather reuses the energy from the cooling system, resulting in negligible fuel consumption. Cooling Principle: The car air conditioning cooling system comprises a compressor, condenser, receiver-drier, expansion valve, evaporator, and blower fan, all connected by copper pipes and high-pressure rubber hoses to form a sealed system. When the cooling system operates, the refrigerant circulates through this closed system in different states.
I've been driving for over 30 years and have firsthand experience with this issue. Using the heater doesn't actually consume much fuel because it mainly utilizes waste heat generated by the engine operation. The fan simply blows the warm air into the car without changing the engine load. However, using the air conditioner in summer is different. The AC compressor is driven by the engine, which adds extra workload to the engine and thus consumes more gasoline. Specifically, using the AC can increase fuel consumption by 10-20%, while using the heater has almost no effect. I remember during long-distance trips in the past, using the heater in winter was very comfortable with no noticeable change in fuel consumption. But in summer, turning on the AC would make the fuel gauge drop significantly. So overall, air conditioning consumes more fuel. I recommend using the heater without worry in winter and reducing AC usage in summer, such as opening windows or turning on the AC only when parked, which can save a lot of money.
