Does Using Air Conditioning on Highways Consume More Fuel?
1 Answers
Highway driving with air conditioning has minimal impact on fuel consumption. While using air conditioning inevitably consumes more fuel, generally, car configurations mainly include manual and automatic air conditioning systems. Manual air conditioning systems typically use a fixed-displacement compressor, where adjusting the fan speed has no effect on the compressor. Once the air conditioning is turned on for cooling, the compressor operates at full speed continuously, so there is no concept of fuel-saving or not. More details are as follows: Note 1: Adjusting the temperature in manual air conditioning merely mixes varying amounts of hot air with the cold air. In practical use, the cabin temperature rarely reaches conditions that would stop the compressor. Simply put, this type of fixed-displacement compressor runs at full speed once activated and does not shut off; thus, even if the temperature is set higher, it does not save fuel. Note 2: Automatic air conditioning can also use fixed-displacement compressors, operating on the same principle as manual systems but with an added automatic temperature control feature. It automatically selects between "pure cold air" or "mixed cold and hot air" based on the difference between the cabin temperature and the set temperature and adjusts the fan speed accordingly. Therefore, the set temperature has no relation to fuel efficiency—using air conditioning will always consume more fuel.
