Ford Mercury Villager 1997 Owner's Manual page 72

The ATC maintains the temperature you select and
automatically controls the airflow for your comfort. It also allows
you to override the automatic operation of airflow and fan
speed with manual function selector buttons and the fan speed
dial.
When you select the AUTOMATIC button, the system determines
airflow location and fan speed automatically. It also
automatically determines whether you will be receiving fresh
outside airflow, recirculated interior airflow, or a combination of
both. You can manually override the airflow source (outside
or recirculated air) and airflow location by selecting one of the
function selector buttons. You can also manually override the fan
speed by rotating the fan speed dial.
Whether you operate in the AUTOMATIC mode or manually
override the AUTOMATIC mode settings, the ATC will continue
to maintain the air temperature you have selected. However,
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