Chrysler DODGE D150 1993 Service Manual page 1438

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• — • • HEATING AND AIR CONDITIONING 24 - 1
C O N T E N T S
page
CLIMATE CONTROL SYSTEM . . . . . . . . . . . . . 21 REFRIGERANT SYSTEM SERWICE
COMPRESSOR SERWICE (SD-709) . . . . . . . . . 21 PROCEDURES . . . . . . . . . . . . .
DIAGNOSTIC PROCEDURES 3 TORQUE SPECIFICATIONS
GENERAL INFORMATION 1
page
. 17
. 31
G E N E R A L I N F O R M A T I O N
HEATER SYSTEM
All models use a Blend-Air type heater. Outside air
enters the heater through the cowl opening and
passes through a plenum chamber to the heater core.
Air intake openings must be kept free of snow, ice
and other obstructions for the heater system to pick
up sufficient outside air. A temperature control door
in the heater housing directs incoming air through
the heater core and/or the heater core bypass. The
amount of blend (heated and non-heated air) is deter­
mined by the setting of the temperature lever on the
instrument panel. Direction of the blended air is con­
trolled by the HEAT-DEFROST lever on the instru­
ment panel.
The blower switch and resistor block controls the
speed of the blower motor. This in turn controls the
velocity of the air flow from the heater outlets.
The resistor block consists of 2 helical wound wire
resistors connected to terminals which are mechani­
cally attached to a glass-filled phenolic board. This
assembly is bolted to the plenum.
The blower switch controls the blower motor speed
by selectively connecting the resistors in series to the
blower motor.
A self-adjusting clip, on each of 2 control cables has
been incorporated to simplify cable adjustment. This
clip snaps onto the control cable core wire and will
slide along the wire under a specific load to provide
an automatic cable adjustment.
AIR CONDITIONING SYSTEM
Air intake openings must be kept free of snow, ice
and other obstructions for the air conditioning sys­
tem to pick up sufficient outside air.
COMPONENTS
• C O M P R E S S O R - T h e seven piston SD-709 com­
pressor is used on all vehicles. This compressor com­
presses the low pressure refrigerant vapor into a
high pressure, high temperature vapor.
• CLUTCH PULLEY AND C O I L - T h e s e are
mounted on the compressor, providing a convenient
way to drive it and disengage it in accordance to the
cooling needs.
• C O N D E N S E R - T h e condenser is located in front
of the radiator. Its function is to cool the hot, high
pressure refrigerant gas causing it to condense into
high pressure liquid refrigerant.
• FILTER-DRIER—The filter-drier is used to remove
any traces of moisture from the refrigerant system.
This component incorporates the sight glass and the
high pressure relief valve.
• SIGHT G L A S S - T h e sight glass is provided as a
diagnostic tool to observe refrigerant flow and indi­
cate refrigerant level. It is located at the top of the
filter drier.
• HIGH -PRESSURE RELIEF V A L V E - T h i s is a
safety device designed to open automatically if the
system pressure reaches a predetermined level. This
will prevent system component damage.
• EXPANSION (H) V A L V E - T h e expansion (H)
valve is used to meter refrigerant into the evaporator
in accordance with cooling requirements.
• EVAPORATOR C O I L - T h e evaporator coil is lo­
cated in the A/C unit. Its function is to cool and de-
humidify the air before it enters the vehicle.
• FREEZE C O N T R O L - T h e main function of freeze
control is to prevent water on the evaporator coil face
from freezing which restricts the airflow. An elec­
tronic temperature cycling switch is located on the
refrigerant plumbing (suction line) near the H-Valve.
The switch turns the compressor ON-OFF depending
on the temperature in the suction line. The switch is
a sealed, specially calibrated unit. If found defective,
the switch must be replaced.
• REFRIGERANT L I N E S - T h e s e lines are needed
to carry the refrigerant between the various system
components.
• CONDENSATE DRAIN T U B E - C o n d e n s a t i o n
which accumulates on the bottom of the evaporator
H E A T I N G A N D A I R C O N D I T I O N I N G