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Regular first, then MAX.

You want the inside air COOLER than the OUTSIDE when you hit MAX, else it's got to work harder.

RwP
 

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I've always maintained using fresh air (regular setting) is better when the car is hotter inside than it is outside. That way you're blowing the coolest available air over the evaporator. Then once the temperature inside is about the same as it is outside, using max will continue cooling faster due to the cooler inlet temps.

That said... the Mark VIII's EATC, when in full auto mode, will set it to max A/C if it's really hot in the car, regardless of what it is outside. Then once it cools down, it switches to regular. More than once (when the charge was low) it would run on max for a while and once it had sufficiently cooled the car off, it would switch to regular but then back to max after a couple minutes, back to regular etc. etc. That would seem to prove that using max cools faster than fresh air...

Maybe it's faster cooling despite being hotter air than what's available outside due to the smaller volume of air being cooled continuously - rather than dumping cooler in, mixing with the hot air and losing that through the vent due to pressure differential? Perhaps the dehumidification factor plays a role as well - smaller volume of air = less moisture to condense = less cooling energy required... :zdunno:
 

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I say MAX all the way if the car is really hot inside. That's why they call it MAX! It "sounds" like it's blowing harder. Seems to cool better. No reason to keep pulling in humid outside air in extreme conditions - 90+.

In pollen season, my HVAC is either off or max. No reason to coat the inside of the car with yellow stuff.

Al
 

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FWIW, the difference between "regular" and "max" a/c is air re-circulation mode off or on, respectively. "Max" a/c will always be colder because it's pulling air from inside the car, which has already been cooled by the system.

That being said, if you live in areas like I do that bake your car hot enough for the oil to boil out of the leather on your shift knob, it would make a little sense that starting in "regular" mode cooling off 103° air would fetch better results initially as opposed to trying to cool off 140°+ air.... if one would ever remember or bother with it.
 

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Discussion Starter #6
FWIW, the difference between "regular" and "max" a/c is air re-circulation mode off or on, respectively. "Max" a/c will always be colder because it's pulling air from inside the car, which has already been cooled by the system.

That being said, if you live in areas like I do that bake your car hot enough for the oil to boil out of the leather on your shift knob, it would make a little sense that starting in "regular" mode cooling off 103° air would fetch better results initially as opposed to trying to cool off 140°+ air.... if one would ever remember or bother with it.
Exactly what I was thinking. It's hotter-n-hell in TX, and it makes sense to me to cool off the furnace air inside before going to the recirculate mode in MAX Thanks to all for your input.
 
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