Re: A/C recirculation/warm air from dash ponderings...

["G. Benedikt Rochow" <rochow@segosf.hlo.dec.com>]

> >I'm guessing that I'm not the only one to be slightly annoyed
> >by the presumption that I always want "fresh" air when I want 
> >heat/cooling, as well as no warm air from the dash vents....
> 
> I always get a lot of hate mail when this thread comes up but from the
> prospective of people who design these things for a living, recirculation is
> a necessary evil.
> 
> It is intended only to be used for maximum A/C cooldown in places like here
> in Texas. It is also useful for a short burst when driving through a cloud
> of dust or exhaust gas or the like. 

Zigactly. That's what I need it for (as well as maybe the first
3 minutes of heat after starting with a cold engine at 
noticably sub-freezing temps).

> 
> Extended driving in recirc will do the following:
 
> While it is true that some people understand all this and can make good use

I do. I grew up around enough diesel cars and lorries (and early
rotten-egg-catalyst VWs) to have plenty of experience with the
reasons for use..

> of manual control in certain situations, I guarantee that most people do not
> have a clue (members of the list excluded). Therefore most manufacturers
> provide recirc only in the max A/C position and many that once provided the
> button are going away from it.

I think the "stuffy" air makes it plenty obvious that some
fresh air is needed.
 
> No warm air from the center dash vents is a design for cars with a heater
> but no A/C. It works well in winter where you drive with heated air on the
> floor and can manually open the center vents a little to allow cold air to
> the face.

I have not seen a separate-fresh-air-dash-vent in any recent car besides
R4s. Anyway, I want warm air on my hands, not cold air on my face!
??

> It is, however, a disaster in an A/C car. The air from the center vents can
> become bone chilling at moderate conditions.

Hmm? When I want cold air, I get it from the dash anyway. When I want
warm air and can't get it from the dash is where my alteration
comes in.
As *my* particular car has a non-functional cooling mechanism,
it's different anyway, but I'm still talking about when it
is absurdly cold, and I'd like the small amount of
warmth the car can provide also on my hands.
 
> 
> The SAE (Society of Automotive Engineers) has a proposal being considered to
> require 20% outside air in recirc mode. Use of 100% recirculation would
> require a timer to switch back to outside air in 10 minutes.

Oh please no. My Caprice has the partial-outside recirc mode,
and it's not nice at all.

> 
> So, that's the party line. I am now prepared for the onslaught of objections.

You should be :)
Though I can live with the timer, there are enough cars where
this is significant extra machinery, as the inside/recirc 
mechanism would otherwise be a mnual cable-driven flap.

-gbr