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I have (3) Buick LeSabre's, (2) have manual climate controllers and work as what I think is the expected behavior, when the heat button is on, the air dampers default to sourcing outside air into the cabin and when the Recirc button is pressed, it recirculates cabin-air without turning on the AC compressor. The third LeSabre has the automatic climate controller, which behaves pretty much the same except when the Temp is increased (there is no heat button on these) and when the Recirc button is switched on, the air recirculates (as expected) but the AC Compressor turns on (regardless of the temperature setting). This 'appears' to be 'by design' because I had a Buick Regal with the automatic climate controller that behaved the same and I've read on other forums where the 'prevailing knowledge' is this is by design. I'm curious if anyone (who shares my opinion that the compressor should not turn on when the temp setting is increased and Recirc Button is on), has come up with any way to make the automatic controller not switch on the AC compressor when the temp is increased and when the Recirc button is on? Thank you for any input.

Most (if not all?) automatic HVAC systems will run the compressor even when set to heat, it's done at least in part to remove humidity from the air to reduce fogging up the windows.

Here's the Description and Operation info for the automatic climate control from GM's factory service manual, I referenced the 2005 but other years should be similar. Air Delivery and Air Temperature

Thank you for your response and the links. Right, this is what I thought, the problem that I see with this philosophy is with the manual controllers (on my 2 other LeSabre's), it does not not call for the compressor (when the Recirc button is pressed) and I've never had an issue with Windows fogging, primarily because I only desire recirculating cabin air when its quite cold outside (this morning it was 19 degrees f) and when its that cold (or colder) all one desires is heat. I'm located in the southern U.S., so cold mornings are not so frequent, I can only imagine that the folks in the northern U.S. or Canada find this to be quite frustrating.