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      02-06-2019, 01:30 PM   #1014
TajoMan
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Drives: M240 xdrive, X3M40i
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Quote:
Originally Posted by albertw View Post
Thanks for the great post.

Question: I've read in several different magazines that air conditioning typically draws 1/3 hp, but that's not the greatest source of facts. Is the 5 ~ 7 hp you quoted peak or average draw?

If it's average, then it is a very substantial addition to the power required to maintain a steady highway speed. If it's even half of that on a day when running the AC is optional, it's another excellent reason for me to keep it off.
Power draw from AC compressor is highly varied by ambient condition.

If ambient is about 100F/40%, AC compressor will take about 5~7hp in fresh air mode, continuously.
If AC is left in recirculation mode, then it will take about 2 hp, after cabin cooled down.

If ambient is 70~80F, AC will be mostly stay in fresh air mode and it will take about 0.5~2hp. (again, highly varied by temp and humidity)

1/3 hp is when the ambient is very mild (50~60F).

BTW, car needs about 25~30 hp to maintain highway speed. (~70mph)
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