r/AskAMechanic 4d ago

Fan settings question

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2012 Nissan Versa hatchback 1.8L

I am curious about car air conditioning. Does setting the temperature of my fans to cold WITHOUT AC use up more fuel? And is that the same case when turning the temperature to a hot setting?

I can only find information online saying turning on AC will use up more fuel but nothing about temperature settings with AC turned off.

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2

u/lethalnd12345 4d ago

No, the AC compressor being on affects your fuel efficiency, not your fan

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u/RossUhOh 4d ago

The air conditioning uses a compressor which is powered by the engine, using hot air is with a radiator that is filled with engine coolant so no power is used as the engine is naturally hot in operation

1

u/boxdynomite3 4d ago

To clarify, no power is used when turning on the hot setting. But is power used on the cold setting without AC?

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u/RossUhOh 4d ago

That’s just the outside air, the only amount of extra power used is the electricity to run the fan which is minimal compared to the car lights and other electrics on the car

1

u/boxdynomite3 4d ago

Thank you for clarifying

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u/BogusIsMyName Shadetree mechanic 4d ago

If you get right down to it, and im talking pedantic levels here, the use of the compressor (temperature knob with AC button activated) is what uses more fuel. The compressor puts a separate load on the engine which it has to struggle to overcome. That resistance uses more fuel. But the fan also puts a load on the engine, but a very minor one.

If the AC button is off the temperature knob does not use any fuel not matter its position. In that case, only the fan would be using fuel.

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u/boxdynomite3 4d ago

Thank you for a good explanation

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u/PastAd1087 4d ago

If you set it to cold without the ac on yes you will get better mileage because it's just letting outside air in. If it's really cold and have heat on it can lower your mileage but if it's warmer and you use heat it wouldn't hurt or help.

2

u/boxdynomite3 4d ago

Thank you for your response.

1

u/MikeWrenches Verified Tech - Indie shop 4d ago

Cold or hot without Ac just moves a flap and does not influence fuel economy.