Dodge RAM 1500 1998 Owner's Manual page 2488

DR
HEATING & AIR CONDITIONING
DESCRIPTION
DESCRIPTION - ENGINE COOLING
SYSTEM REQUIREMENTS . . . . . . . . . . . . . . . 1
DESCRIPTION - HEATER AND AIR
CONDITIONER . . . . . . . . . . . . . . . . . . . . . . . . 1
OPERATION - HEATER AND AIR
CONDITIONER . . . . . . . . . . . . . . . . . . . . . . . . 1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - A/C
PERFORMANCE . . . . . . . . . . . . . . . . . . . . . . . 3
HEATING & AIR
CONDITIONING
DESCRIPTION
DESCRIPTION - ENGINE COOLING SYSTEM
REQUIREMENTS
To maintain the performance level of the heating,
ventilation and air conditioning (HVAC) system, the
engine cooling system must be properly maintained.
The use of a bug screen is not recommended. Any
obstructions in front of the radiator or A/C condenser
will reduce the performance of the A/C and engine
cooling systems.
The engine cooling system includes the radiator,
thermostat, radiator hoses and the engine coolant
pump. Refer to Cooling for more information before
opening or attempting any service to the engine cool-
ing system.
DESCRIPTION - HEATER AND AIR
CONDITIONER
A manually controlled single zone type heating-air
conditioning system or a manually controlled dual
zone type heating-air conditioning system is available
on this model.
All vehicles are equipped with a common heater,
ventilation and air conditioning (HVAC) housing (Fig.
1). The system combines air conditioning, heating,
and ventilating capabilities in a single unit housing
mounted within the passenger compartment under
the instrument panel. The HVAC housing includes:
• Blower motor
• Blower motor resistor block
HEATING & AIR CONDITIONING
TABLE OF CONTENTS
page
HEATING & AIR CONDITIONING
DIAGNOSIS AND TESTING - HEATER
PERFORMANCE TEST . . . . . . . . . . . . . . . . . . 6
SPECIFICATIONS - A/C SYSTEM
CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
DISTRIBUTION . . . . . . . . . . . . . . . . . . . . . . . . . . 26
PLUMBING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
• Heater core
• Evaporator coil
• Blend door and actuator
• Defrost door and actuator
• Mode door and actuator
• Recirculation door and actuator
Based upon the system and mode selected, condi-
tioned air can exit the HVAC housing through one or
a combination of the three main housing outlets:
defrost, panel or floor. The defrost outlet is located on
the top of the housing, the panel outlet is located on
the face of the housing and the floor outlet is located
on the bottom of the housing. Once the conditioned
air exits the unit housing, it is further directed
through molded plastic ducts to the various outlets in
the vehicle interior. These outlets and their locations
are as follows:
• Defroster Outlet - A single large defroster out-
let is located in the center of the instrument panel
top cover, near the base of the windshield.
• Side Window Demister Outlets - There are
two side window demister outlets, one is located at
each outboard end of the instrument panel top cover,
near the belt line at the A-pillars.
• Panel Outlets - There are four panel outlets in
the instrument panel, one located near each outboard
end of the instrument panel facing the rear of the
vehicle and two located near the top of the instru-
ment panel center bezel.
• Front Floor Outlets - There are two front floor
outlets, one located above each side of the floor panel
center tunnel near the dash panel.
OPERATION - HEATER AND AIR CONDITIONER
The heating and air conditioning systems pulls
outside (ambient) air through the cowl opening at the
base of the windshield, then into the plenum cham-
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