Ford 1998 Windstar Owner's Manual page 79

Controls and Features
The climate controls — main and auxiliary system A/C — Heater System — if
equipped
The auxiliary system is controlled exclusively by the 9-position
switch. If the control is turned to the left, cool air will be
delivered at the beltline and overhead. If the control is turned
to the right, warm air will be delivered to the floor area. The
further left or right from the OFF position the control is turned,
the higher the fan speed.
The standard heating system and the heating portion of the
heating and air conditioning system are essentially identical.
There is one exception, however; the air conditioning
compressor will automatically engage when the P
(DEFROST/FLOOR) or V (DEFROST) position is selected to
aid in defogging and defrosting the inside glass when the
outside temperature is above approximately 45˚F (7˚C). Refer to
the heating system operating instructions covered previously for
a more detailed explanation of heating system operation.
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