There are two separate control systems invovled here.
The "different locations" are your "MODE SELECT" functions controlled by the center knob on the heater control panel. Those are all vacuum operated, and are not instantaneous upon moving selector knob (may take 1-2 seconds to react).
The TEMPERATURE control is an electric stepper motor connected to the shaft on the bottom of the "Blend door" on the heater box. This motor is located on the heater box directly above the transmission tunnel. It can be remove without touching anything else and confirmed to function. If it is OK, then the blend door itself is jammed/broken and requires the heater box to be removed to correct the issue.
1992 XJ -- stock (RIP)
2000 XJ -- lots of basic mods. Sold to fellow forum member. I miss it.
2014 JK -- the project is just starting!
For Sale to Good Home---2000 XJ Factory Service Manual (Printed Version) PM for details.