Case 580SR Service Manual page 785

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EVAPORATOR
The evaporator is located beneath the cab seat and
consists of a number of turns of continuous coils
mounted in a series of thin cooling fins to provide a
maximum of heat transfer in a minimum amount of
space.
Low temperature refrigerant in the evaporator ab-
sorbs heat from the hotter air in the operator's com-
partment, thereby cooling the air.
Air Recirculation
An intake grille is located on the left side of the seat
base. A portion of the air flow will recirculate through
the evaporator.
Filter General
The blower fan, draws warm air from outside the cab
through the intake filter (2) below the cab floor and a
ready cooled dehumidified air through the recircula-
tion grille (1). The air passes over the evaporator
then into the cab through the six louvered vents.
Two vents are located on the front instrument panel
to direct air onto the windshield. Two are located at
the base of the rear posts to direct air onto the rear
window. Two additional vents are located at the front
and rear of the seat base to direct air at the opera-
tor's feet.
Blower Fan
The blower motor is controlled by a three-speed
switch (3) which uses a variable resistor to change
the fan speed.
High blower speed provides the greatest volume of
circulated air, however, a slower speed will allow the
air to contact the cooling fins and coils of the evapo-
rator for a longer period resulting in the warm air giv-
ing up more heat to the cooler refrigerant. Therefore,
the coldest air temperature is obtained when the
blower fan is operated at the lowest speed.
SECTION 50 - CAB HEATING AND AIR CONDITIONING
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