Mercury 1999 Villager Owner's Manual page 37

Controls and features
The rear A/C fan speed control allows rear passengers to control the
volume of air that is distributed from the rear registers.
The rear A/C system is controlled from the main climate control system
on the instrument panel.
The rear seat A/C system is controlled from the main climate control
system on the instrument panel.
REAR
A/C
1 OFF
2
3
MAX
4
A/C
OFF REAR A/C 1 2 3 4
A/C
37