Ford Windstar Owner's Manual page 87

In V (DEFROST), most of the air is directed through the
defrosters and onto the windshield. A small amount is diverted
to the floor.
Heater Controls (Heater-Only Vehicles)
The fan speed, temperature, and function controls are essentially
the same as the A/C controls described previously with the
exception that the control assembly has no function settings for
MAX A/C and A/C and no A/C compressor operation is
provided in any of the function settings. An illustration of the
control for a heater-only system follows.
Climate control panel — Heater-Only System
Turning On the Heat
Heat will not be available until the engine has been running for
sufficient time as indicated by the engine coolant temperature
gauge.
To heat the inside of your vehicle:
Turn the Function Selector Knob to R (FLOOR). Outside
1.
air is drawn in and directed into the passenger compartment
through the floor outlets. Small quantities of air are also
directed to the defrost and side window demist outlets.
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