That sounds more like the description of the small versions (600/700 or the older 300/500) and not the 800 (and i suspect the 900). The larger models have actually three temperature selectors for the three zones that are controlled (cockpit, forward and aft cabin).
Found in some document on smartcockpit.com (am not allowed to use my companies documentation or i could be fired):
Zone Temperature Control
There are three zones: flight deck, forward cabin and aft cabin. Desired zone temperature is set by adjusting the individual Temperature Selectors. The selector range is approximately 65°F (18°C) to 85°F (30°C).
The packs produce an air temperature that satisfies the zone which requires the most cooling. Zone temperature is controlled by introducing the proper amount of trim air to the zone supply ducts. The quantity of trim air is regulated by individual modulating valves.
ballyboley refers quite correctly to the fixed temperature if you switch the temperature selectors to off. And yes, i wish Boeing put the selectors out for the cabin crew to control, would save all the interphone calls during the flights (well, forward and aft cabin, not flight deck please!).
Auto is not a fixed setting, it is rather the selectable temperature range and the relevant controller tries to control the temperature in the cabin area to that temperature. That is not allways done very fast or successfull, and if the ducts and sensors are not cleaned often enough it might prove quite difficult to achieve a constant setting that works throughout the flight.