I know we all just tend to gloss over the manual, "Yea, yea, heater operation, Don't need to read that, Get to the good stuff..." But there is a nugget sitting in that section; there are five ways to line up the heater vents -

Dash
Floor*
Screen*
Dash&floor
Floor&screen

all as expected, but read on and you find the ones I marked with asterisks "when selected, these positions will run the air conditioner, whether the switch is ON or OFF" !

followed by "the air conditioner system light WILL NOT
ILLUMINATE"

So if fuel economy is vital to you, and you want to avoid using the A/C, don't put the system to Floor or Screen.....
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doc

 

Shouldn't it be: 1)Screen and 2) Floor&Screen
Not Floor alone?

Most Defrosters (screen) run the A/C to defog the window.

 

Thats what I thought, but the book says different - if you put the system to floor outlets only - the a/c is on, like it or not, and the a/c light is OFF.!
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doc

 

Could it be attributed to the fact that the foot well becomes quite toasty after driving around for a while?

Still you'd expect the two controls to be orthogonal.

/Elak