Another AC question

[Bob Allen]

When using AC is it better to have the recirculation funtion on? I thought that recirculating the air actually makes the AC more effective because it doesn't have to keep processing "new" incoming air, so that it takes less work maintaining the temp and humidity. Yes? No? Does the AC automatically decide to use recirc or not?

[Presto]

By default, AC is set to recirculate the air. I leave it on recirculate since I subscribe to the theory that you described.

[zenMachine]

There's an even more important reason for recirculating:

To minimize your exposure to pollution, Conrad Schneider, advocacy director for the Clean Air Task Force, says drivers should try to avoid roads filled with trucks' diesel exhaust. If you can't avoid traveling with trucks, close your windows and set your air to recirculate...[/b]

The Most Unhealthy Commutes in America

[telstar]

<div class='quotetop'>QUOTE(Angel Flight Pilot @ Aug 6 2007, 12:40 PM) [snapback]491351[/snapback]</div>

When using AC is it better to have the recirculation funtion on? I thought that recirculating the air actually makes the AC more effective because it doesn't have to keep processing "new" incoming air, so that it takes less work maintaining the temp and humidity. Yes? No? Does the AC automatically decide to use recirc or not?
[/b]

I may be way off here, but back in the "old days" when in recirculate mode it meant the compressor ran continually and, of course, recirculated the cabin air not letting outside air in. If that is the case still, then running the compressor all the time will take more power than with it running off and on on the normal setting. Perhaps one of the techs could chime in as to whether the AC compressor runs all the time when on recirculate...

[David Beale]

If you use "auto" A/C, which is the default, BTW, my observations indicate the system uses recirc and fresh air, according to its' own desires (programming, actually).

Use "auto" and let it do its' thing. It appears to be smarter than we.

[Texas911]

Yea, leave it on auto. It'll set the recirc on if it needs it. Usually to help cool the interior quickly then go to fresh air. Using fresh air is adviced so the condensers don't grow mold and on the very very rare chance that carbon monoxide gets trapped inside your car.

[KTPhil]

"I may be way off here, but back in the "old days" when in recirculate mode it meant the compressor ran continually and, of course, recirculated the cabin air not letting outside air in. "

GM systems sort of used to work that way. They labeled the switch position "MAX COLD" and it really meant RECIRC. Older systems ran the compresser all the time and blended hot air to get the set temperature output. This wasteful practice was changed in the mid-late 70s as gas prices hit the (don't laugh) astronomical price of $1 per gallon. ;-)

[richard schumacher]

In the Prius recirc does not run the compressor continuously. Recirc at will. I recirc continuously, except sometimes if needed during defrost, to keep the cabin and my lungs cleaner.