Dodge Dakota 2001, Service Manual

Page: 2166 / 2307

HEATING & AIR CONDITIONING
TABLE OF CONTENTS
page page
HEATING & AIR CONDITIONING
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
DIAGNOSIS AND TESTING . . . . . . . . . . . . . . . . . . 1
A/C PERFORMANCE . . . . . . . . . . . . . . . . . . . . . 1
DIAGNOSIS AND TESTING - HEATER
PERFORMANCE. . . . . . . . . . . . . . . . . . . . . . . . . 5
STANDARD PROCEDURE . . . . . . . . . . . . . . . . . . . 7
REFRIGERANT SYSTEM SERVICE
EQUIPMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . 8
CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
DISTRIBUTION . . . . . . . . . . . . . . . . . . . . . . . . . . 25
PLUMBING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
HEATING & AIR
CONDITIONING
DESCRIPTION - COOLING SYSTEM
REQUIREMENTS
To maintain the performance level of the HVAC
system, the engine cooling system must be properly
maintained. The use of a bug screen is not recom-
mended. Any obstructions in front of the radiator or
condenser will reduce the performance of the air con-
ditioning and engine cooling systems.
The engine cooling system includes the heater core
and the heater hoses. Refer to Cooling for more infor-
mation before the opening of, or attempting any ser-
vice to the engine cooling system.
DESCRIPTION - REFRIGERANT SYSTEM
SERVICE PORTS
The two refrigerant system service ports are used
to charge, recover/recycle, evacuate, and test the air
conditioning refrigerant system. Unique service port
coupler sizes are used on the R-134a system, to
ensure that the refrigerant system is not accidentally
contaminated by the use of the wrong refrigerant
(R-12), or refrigerant system service equipment.
OPERATION - REFRIGERANT SYSTEM SERVICE
PORTS
The high pressure service port is located on the liq-
uid line between the condenser and the evaporator,
near the front of the engine compartment. The low
pressure service port is located on the compressor
manifold, directly over the suction port of the com-
pressor, for 5.9L Engine. It is on the suction line
between the compressor and the evaporator for the
4.7L engine.
Each of the service ports has a threaded plastic
protective cap installed over it from the factory. After
servicing the refrigerant system, always reinstall
both of the service port caps.
DIAGNOSIS AND TESTING - A/C
PERFORMANCE
The air conditioning system is designed to provide
the passenger compartment with low temperature
and low humidity air. The evaporator, located in the
HVAC housing on the dash panel below the instru-
ment panel, is cooled to temperatures near the freez-
ing point. As warm damp air passes through the
cooled evaporator, the air transfers its heat to the
refrigerant in the evaporator tubes and the moisture
in the air condenses on the evaporator fins. During
periods of high heat and humidity, an air condition-
ing system will be more effective in the recirculation
mode (Max-A/C). With the system in the recirculation
mode, only air from the passenger compartment
passes through the evaporator. As the passenger com-
partment air dehumidifies, the air conditioning sys-
tem performance levels improve.
Humidity has an important bearing on the temper-
ature of the air delivered to the interior of the vehi-
cle. It is important to understand the effect that
humidity has on the performance of the air condition-
ing system. When humidity is high, the evaporator
has to perform a double duty. It must lower the air
temperature, and it must lower the temperature of
the moisture in the air that condenses on the evapo-
rator fins. Condensing the moisture in the air trans-
fers heat energy into the evaporator fins and tubing.
This reduces the amount of heat the evaporator can
absorb from the air. High humidity greatly reduces
the ability of the evaporator to lower the temperature
of the air.
However, evaporator capacity used to reduce the
amount of moisture in the air is not wasted. Wring-
ing some of the moisture out of the air entering the
vehicle adds to the comfort of the passengers.
Although, an owner may expect too much from their
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