Quote:
Originally Posted by Homeslice
I've heard people say that the only thing Max A/C does is simply operate the flap which shuts off outside air, so that air inside the car gets cold faster. But if that's all it does, then why does the fan speed increase as well?
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My guess, and it may be what Particle man meant as well, is when the A/C is set to get fresh air it is putting new air in the car. The old air has to be forced out somewhere creating higher pressure in the cabin. The fan runs slower because it has to overcome that pressure differential to get the new air in the cabin. When set on recirc it is drawing air from the cabin, cooling it, then replacing it back in the cabin. The fan does not have to work against the increased cabin pressure, its job is easier, and as a result it can run faster. I know in my truck when the A/C is set to get outside air its output increases if I crack the window open.