w108 - Defrost with AC?

[vandor]

I have red the '72 w108 owners manual, however something is not clear.
Is the ducting for the AC separate from the heater? I would assume so, but the manual seems to indicate that from some of the vents one can get both hot or cold air.
If they are not separate, is it possible to use the AC to defrost the windshield? On newer cars the AC turns on automatically on the defrost setting, as it takes the humidity out of the air and defrosts much faster than heat alone.
Not that I'd drive the car much in conditions where it would need defrosting, but I'd like to know how the system works.
Thanks,

Csaba
'72 280SEL 4.5

[Palolo]

Yes and no.

The heater, or more accurately, the blower, will defrost windshield with outside air, heated or unheated. (Its air intake is beneath the cowl vent). The blower will also route air to the footwells, front and rear if the upper right lever is to the right.

The left round vent will give you either outside air, or blower air (depending on the lever position to close the intake flap) and if your car has A/C, there is a duct running under the dash to that left round vent too, so in theory you can get cooled air there too.

The right round vent will give you A/C, along with the obvious under dash A/C vents.

The A/C unit doesn't send air to the windshield...

Not sure if that helps...

[vandor]

OK thanks, that's what I thought.
Thanks,

Csaba