On a hot day and traveling in a car, which method of keeping the occupants comfortable with the A/C is more energy and fuel efficient?
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Set the thermostat to a lower temperature and keep fan speed to the lowest setting
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Set the thermostat to a slightly higher temperature and compensate by setting the fan to a higher speed so you can feel cool enough with the breeze
There’s a few things a bunch of other commenters are getting wrong, at least from my understanding.
The AC compressor is run by a belt from the engine. Unlike a home AC, a vehicles AC is either on or off. There is no cycling. The temp control is just changing how much outside air comes in, or how much heat is drawn from the engine.
The fan speed is not going to effect anything at all. The alternator spins to generate electricity to recharge the battery, but the amount of energy required to spin it doesn’t change based on how much electricity is being drawn.
Tamping your AC down in any way, whether by lowering fan speed, or increasing the temperature is less efficient. Use it at it’s coldest temp and highest fan speed if you’re going to use it at all.
Edit: I almost forgot to add that AC efficiency is going to be more closely tied to your driving speed and outside air temperature. Driving faster makes your AC more efficient (not necessarily your whole car). More air passing over the evaporators means more heat released from your AC to the outside, which makes colder air in your car. The colder the air outdoors, the more heat the AC can release to the outdoors, which means colder air in your car.
As for EVs, I have entirely no clue, but I would assume it’s a similar situation.
Edit: I may be entirely wrong. I’m not sure about anything anymore. I know a guy who knows all about these things, let me get him down here tomorrow and we can go from there.
Edit 2: I meant to make an edit and accidentally deleted my comment. I actually did meet with my guy. Im also too tired to work a phone. Can’t wait to share what I understood from what my guy said.
A vehicle AC compressor does cycle. There is a clutch on the pulley attached to the compressed that engages the compressor or lets the pulley free wheel.
Also the alternator absolutely takes more power from the engine in proportion to how much energy it’s putting out.
What is this complete nonsense of an answer.
I just accidentally deleted my original comment.
Heres I what I deleted.
There’s a few things a bunch of other commenters are getting wrong, at least from my understanding.
The AC compressor is run by a belt from the engine. Unlike a home AC, a vehicles AC is either on or off. There is no cycling. The temp control is just changing how much outside air comes in, or how much heat is drawn from the engine.
The fan speed is not going to effect anything at all. The alternator spins to generate electricity to recharge the battery, but the amount of energy required to spin it doesn’t change based on how much electricity is being drawn.
Tamping your AC down in any way, whether by lowering fan speed, or increasing the temperature is less efficient. Use it at it’s coldest temp and highest fan speed if you’re going to use it at all.
Edit: I almost forgot to add that AC efficiency is going to be more closely tied to your driving speed and outside air temperature. Driving faster makes your AC more efficient (not necessarily your whole car). More air passing over the evaporators means more heat released from your AC to the outside, which makes colder air in your car. The colder the air outdoors, the more heat the AC can release to the outdoors, which means colder air in your car.
As for EVs, I have entirely no clue, but I would assume it’s a similar situation.
Edit: I may be entirely wrong. I’m not sure about anything anymore. I know a guy who knows all about these things, let me get him down here tomorrow and we can go from there.
I got my guy down here and he told me I was right and wrong. I’ll give the details tomorrow but I can barley work my phone.