Browsing through
http://catalog.gmpartsdirect.co
here's what I gleaned so far, for a 2012 (you can research a 2008):
Automatic temperature controls, Ambient temp sensor $3.84 <-- edit apparently this is already installed in my car (1LT)
+bracket $5.02
+retainer pin $3.06
Automatic temperature controls, In-car sensor $5.18 X 2 (one for center duct, one for lower)
+Sensor retainer $4.34 x 2
Automatic temperature controls, Sunload sensor (aka Auto lamp sensor, W/climate control) $23.94 <--not sure if this is actually different from the light sensor used for auto dimming lights, assuming it is)
Blower motor, Resistor Malibu, w/ATC $106.03
Controls, Dash control unit Malibu, w/Auto Control $248.12
Center duct, W/climate control $8.38 <-- Edit through the dash vents I can see a square punch-out for the sensor retainer, a new center duct may not be needed (speculation)
Lower air duct, W/climate control $23.29 <--Edit it appears the in-car temp sensor is attached to this duct, a new center duct may not be needed (speculation)
Actuators on the Heater/AC Module Assembly would need to be swapped. I did not price them out, maybe about $200+
**The actuators on the Heater A/C module have different connectors, thus a harness swap is necessary.**
**no air conditioner components specified manual vs automatic climate control**
Edit: according to
http://www.tonkinonlineparts.com/showAssembly.aspx?ukey_product=6141164&ukey_assembly=861617 the ambient temp sensor is in front of the radiator, and I can see it on my car (1LT) without auto climate controls.
Some more info here:
http://www.tonkinonlineparts.com/sh...line=8612&ukey_trimlevel=19635&modelYear=2012