A/C question for 2003 Monterey

My car has 3 zone controls - driver, passenger, rear.
When I turn on recirculate and/or the seat heating and cooling, it randomly cuts off after 10-45 minutes. The A/C still runs but it starts
pulling in fresh air and simultaneously turns off the seats.
The dealer is telling me this is normal operation. Once it senses I've reached the desired temp, it is programmed to disable both recirc and the seat heating/cooling.
To me, this sounds like BS.
First, the front has independent zones. If me and my wife are set to different temps (which is common), why would BOTH seats cut off at once? Also, why would seat heating turn off because of the air temperature?
I like to leave it on recirc because their are lots of diesel trucks on the road during my commute. The fumes are pretty strong when I'm drawing air through the a/c. I can't imagine why it would turn off this function instead of just turning down the blower to modulate temperature.
Can anyone point me to a resource that can either confirm or deny what I've been told by the dealer?
Or, does anyone have the same A/C setup in their vehicle who can confirm that it works or doesn't work in that manner?
Any help would be appreciated. After holding my car for five days, the answer they've given me was disappointing at best.
Regards, Bill Shaw Tampa, FL
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Sorry to bump with a self-link, but I've added some more detail on the problem on my blog.
Any insight would be /greatly/ appreciated.
http://inanimatereason.com/2006/07/31/wanna-sell-me-another-mercury /
snipped-for-privacy@gmail.com wrote:

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