RESISTOR-BLOWER MOTOR
DESCRIPTION
The blower motor resistor is mounted to the bottom of
the HVAC housing, directly behind the glove box. The
blower motor resistor consists of a molded plastic
mounting plate (1) with an integral wire connector
receptacle (2). Concealed behind the mounting plate
are coiled resistor wires contained within a ceramic
heat sink (3).
OPERATION
The blower motor resistor is connected to the vehicle electrical system through a dedicated wire lead and connector
of the HVAC wire harness. The blower motor resistor has multiple resistor wires, each of which will reduce the
current flow through the blower motor to change the blower motor speed.
The blower motor control for the heating-A/C system directs the ground path for the blower motor through the cor-
rect resistor wire to obtain the selected speed. With the blower motor control in the lowest speed position, the
ground path for the blower motor is applied through all of the resistor wires. Each higher speed selected with the
blower motor control applies the blower motor ground path through fewer ofthe resistor wires, increasing the blower
motor speed.
The blower motor resistor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
DIAGNOSIS AND TESTING
BLOWER MOTOR RESISTOR
WARNING: On vehicles equipped with airbags, disable the airbag system before attempting any steering
wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the
negative battery (ground) cable, then wait two minutes for the airbag system capacitor to discharge before
performing further diagnosis or service. This is the only sure way to disable the airbag system. Failure to
take the proper precautions could result in accidental airbag deploymentand possible personal injury or
death.
NOTE: For circuit descriptions and diagrams, refer to the appropriate wiring information. The wiring infor-
mation includes wiring diagrams, proper wire and connector repair procedures, further details on wire har-
ness routing and retention, as well as pin-out and location views for the various wire harness connectors,
splices and grounds.
1. Disconnect and isolate the negative battery cable.
2. Disconnect the wire harness connector from the blower motor resistor (Refer to 24 - HEATING & AIR CONDI-
TIONING/CONTROLS/RESISTOR-BLOWER MOTOR - REMOVAL).
SENSOR-EVAPORATOR TEMPERATURE
DESCRIPTION
The evaporator temperature sensor is a two-wire tem-
perature sensing element located at the coldest point
on the face of the A/C evaporator. The probe (1) for
evaporator temperature sensor is attached to the
evaporator coil fins. The wire lead (2) for evaporator
temperature sensor is routed through an opening at
the back of the HVAC housing and the connector (3)
is attached to the HVAC wire harness.
OPERATION
The evaporator temperature sensor monitors the surface temperature of A/C evaporator and supplies an input signal
to the A/C-heater control. The A/C-heater control uses the evaporator temperature sensor input signal to optimize
A/C system performance and to protect the A/C system from evaporator freezing. The evaporator temperature sen-
sor will change its internal resistance in response to the temperatures itmonitors and is connected to the A/C-heater
control through sensor ground circuit and a 5-volt reference signal circuit. As the temperature of the A/C evaporator
decreases, the internal resistance of the evaporator temperature sensordecreases.
The A/C-heater control uses the monitored voltage reading as an indication of evaporator temperature. The A/C-
heater control is programmed to respond to this input by requesting the powertrain control module (PCM) or the
engine control module (ECM) (depending on engine application) to cycle the A/C compressor clutch as necessary to
optimize A/C system performance and to protect the A/C system from evaporatorfreezing(Referto24-HEATING
& AIR CONDITIONING/CONTROLS/COIL-A/C COMPRESSOR CLUTCH - OPERATION formore information).
The evaporator temperature sensor is diagnosed using a scan tool (Refer to24 - HEATING & AIR CONDITIONING
- DIAGNOSIS AND TESTING and to 24 - HVAC Electrical Diagnostics for more information).
The evaporator temperature sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
1. Disconnect and isolate the negative battery cable.
2. Disconnect the wire harness connector (1) from the
A/C pressure transducer (2) located on the A/C dis-
charge line (3).
3. Remove the A/C pressure transducer from the fit-
ting on the A/C discharge line and remove and dis-
card the O-ring seal.
INSTALLATION
NOTE:UseonlythespecifiedO-ringasitismadeofspecialmaterialforR-134a. Use only refrigerant oil of
the type required for the A/C compressor.
1. Lubricate a new rubber O-ring seal (4) with clean
refrigerant oil and install it onto the discharge line
fitting (3).
2. Install the A/C pressure transducer (2) onto the A/C
discharge line. Tighten the A/C pressure transducer
securely.
3. Connect the wire harness connector (1) to the A/C
pressure transducer.
4. Reconnect the negative battery cable.
5.9L DIESEL ENGINE ...................... 343
8.3L ENGINE .............................. 345
OIL-A/C REFRIGERANT
DESCRIPTION ............................... 347
OPERATION ................................. 347
STANDARD PROCEDURE
REFRIGERANT OIL LEVEL ................. 347
REFRIGERANT-A/C
DESCRIPTION ............................... 349OPERATION ................................. 349
TUBE-A/C ORIFICE
DESCRIPTION ............................... 350
OPERATION ................................. 350
DIAGNOSIS AND TESTING
A/C ORIFICE TUBE ........................ 350
PLUMBING
DESCRIPTION
The A/C refrigerant lines and hoses are used to carry the refrigerant between the various A/C system components.
The refrigerant lines and hoses for the R-134a system on this vehicle consist of a barrier-hose design with a nylon
tube sandwiched between rubber layers. The nylon tube helps to contain theR-134a refrigerant, which has a
smaller molecular structure than R-12 refrigerant. The ends of the refrigerant lines are made from lightweight alu-
minum or steel, and commonly use braze-less fittings.
Any kinks or sharp bends in the refrigerant lines and hoses will reduce the capacity of the entire A/C system and
can reduce the flow of refrigerant in the system. The radius of all bends in the flexible hose refrigerant lines should
be at least ten times the diameter of the hose and the refrigerant lines should be routed so they are at least 80
millimeters (3 inches) away from the exhaust manifold(s) and exhaust pipe(s).
OPERATION
High pressures are produced in the refrigerant system when the A/C compressor is operating. Extreme care must
be exercised to make sure that each of the refrigerant system connections is pressure-tight and leak free. It is a
good practice to inspect all flexible hose refrigerant lines at least oncea year to make sure they are in good con-
dition and properly routed.
The refrigerant lines and hoses are coupled to other A/C system componentswith block-type fittings. An O-ring seal,
or a flat steel gasket with an integral O-ring (dual plane seal), is used to mate the refrigerant line fittings with A/C
system components to ensure the integrity of the refrigerant system.
The refrigerant lines and hoses cannot be repaired and, if faulty or damaged, they must be replaced.
WARNING
WARNING: The A/C system contains refrigerant under high pressure. Repairs should only be performed by
qualified service personnel. Severe personal injury or death may result from improper service procedures.
WARNING: Avoid breathing the refrigerant and refrigerant oil vapor or mist. Exposure may irritate the eyes,
nose, and/or throat. Wear eye protection when servicing the A/C refrigerant system. Serious eye injury can
result from direct contact with the refrigerant. If eye contact occurs, seek medical attention immediately.
WARNING: Do not expose the refrigerant to open flame. Poisonous gas is createdwhenrefrigerantis
burned. An electronic leak detector is recommended. Severe personal injury or death may result from
improper service procedures.
WARNING: If accidental system discharge occurs, ventilate the work area before resuming service. Large
amounts of refrigerant released in a closed work area will displace the oxygen and cause suffocation and
death.
WARNING: The evaporation rate of R-134a refrigerant at average temperature and altitude is extremely high.
As a result, anything that comes in contact with the refrigerant will freeze. Always protect the skin or del-
icate objects from direct contact with the refrigerant.
WARNING: The R-134a service equipment or the vehicle refrigerant system should not be pressure tested or
leak tested with compressed air. Some mixtures of air and R-134a have been shown to be combustible at
elevated pressures. These mixtures are potentially dangerous, and may result in fire or explosion causing
property damage, personal injury or death.
WARNING: The engine cooling system is designed to develop internal pressures up to 145 kilopascals (21
pounds per square inch). Do not remove or loosen the coolant pressure cap, cylinder block drain plugs,
radiator drain, radiator hoses, heater hoses, or hose clamps while the engine cooling system is hot and
under pressure. Allow the vehicle to cool for a minimum of 15 minutes beforeopening the cooling system
for service. Failure to observe this warning can result in serious burns from the heated engine coolant.
CAUTION
CAUTION: Never add R-12 to a refrigerant system designed to use R-134a. Do not use R-12 equipment or
parts on an R-134a A/C system. These refrigerants are not compatible and damage to the A/C system will
result.
CAUTION: Never use R-12 refrigerant oil in a A/C system designed to use R-134a refrigerant oil. These
refrigerant oils are not compatible and damage to the A/C system will result.
CAUTION: The use of A/C system sealers may result in damage to A/C refrigerant recovery/evacuation/re-
charging equipment and/or A/C system. Many federal, state/provincial and local regulations prohibit the
recharge of A/C systems with known leaks. DaimlerChrysler recommends thedetection of A/C system leaks
through the use of approved leak detectors and fluorescent leak detectiondyes. Vehicles found with A/C
system sealers should be treated as contaminated and replacement of the entire A/C refrigerant system is
recommended. A/C systems found to be contaminated with A/C system sealers, A/C stop-leak products or
seal conditioners voids the warranty for the A/C system.
CAUTION: Recover the refrigerant before opening any fitting or connection. Open the fittings with caution,
even after the system has been discharged. Never open or loosen a connection before recovering the refrig-
erant.
CAUTION: If equipped, do not remove the secondary retention clip from any spring-lock coupler connection
while the refrigerant system is under pressure. Recover the refrigerant before removing the secondary
retention clip. Open the fittings with caution, even after the system has been discharged. Never open or
loosen a connection before recovering the refrigerant.
CAUTION: The internal parts of the A/C system will remain stable as long as moisture-free refrigerant and
refrigerant oil is used. Abnormal amounts of dirt, moisture or air can upset the chemical stability. This may
cause operational troubles or even serious damage if present in more than very small quantities. Before
disconnecting a component, clean the outside of the fittings thoroughly to prevent contamination from
entering the refrigerant system. Keep service tools and the work area clean. Do not open the refrigerant
system or uncap a replacement component until you are ready to service the system. Immediately after
disconnecting a component from the refrigerant system, seal the open fittings with a cap or plug. This will
prevent contamination from entering the A/C system.
CAUTION: Refrigerant oil will absorb moisture from the atmosphere if leftuncapped. Do not open a con-
tainer of refrigerant oil until you are ready to use it. Replace the cap on the oil container immediately after
using. Store refrigerant oil only in a clean, airtight, and moisture-freecontainer.
CAUTION: Do not overcharge the refrigerant system. Overcharging will cause excessive compressor head
pressure and can cause compressor noise and A/C system failure.
DIAGNOSIS AND TESTING
REFRIGERANT SYSTEM LEAKS
WARNING: R-134a service equipment or vehicle A/C system should not be pressure tested or leak tested
with compressed air. Mixture of air and R-134a can be combustible at elevated pressures. These mixtures
are potentially dangerous and may result in fire or explosion causing property damage, personal injury or
death.
Avoid breathing A/C refrigerant and lubricant vapor or mist. Exposure mayirritate eyes, nose and throat.
Use only approved service equipment meeting SAE requirements to discharge R-134a system. If accidental
system discharge occurs, ventilate work area before resuming service.
NOTE: If the A/C refrigerant system charge is empty or low, a leak in the A/C system is likely. Visually
inspect all A/C lines, fittings and components for an oily residue. Oil residue can be an indicator of an A/C
system leak location.
NOTE: The only way to correctly determine if the refrigerant system is fully charged with R-134a is to com-
pletely evacuate and recharge the A/C system.
Connect a suitable manifold gauge setand determine if the static A/C system pressure is above or below 345 kPa
(50 psi) (refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PROCEDURE - REFRIGERANT
SYSTEM SERVICE EQUIPMENT). If less than 345 kPa (50 psi), proceed to SYSTEMEMPTY . If greater than 345
kPa (50 psi), go to SYSTEM LOW .
SYSTEM EMPTY
1. Evacuate the refrigerant system to the lowest degree of vacuum possible(approximately -88 kPa (- 26 in. Hg) or
greater vacuum) (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT SYSTEM EVACUATE). Determine if the system holds a vacuum for 15 minutes. If vacuum is
held, a leak is probably not present. If system will not maintain vacuum level, proceed to Step 2.
2. Prepare and dispense 0.284 kilograms (10 ounces) of R-134a refrigerantinto the evacuated refrigerant system
(Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE) and proceed to Step 1 of the System Low procedure.
SYSTEM LOW
1. Position the vehicle in a wind-freework area. This will aid in detectingsmall leaks.
2. Operate the heating-A/C system with the engine at idle under the following conditions for at least five minutes.
Doors or windows open
Transmission in Park or Neutral with the parking brake set (depending on application)
A/C-heater controls set to outside air, full cool, panel mode, high blowerand with A/C compressor engaged
CAUTION: A leak detector only designed for R-12 refrigerant will not detect leaks in an R-134a refrigerant
system.
3. Shut the vehicle Off and wait 2-7 minutes. Then use an electronic leak detector that is designed to detect R-134a
refrigerant and search for leaks. Fittings, lines or components that appear to be oily usually indicate a refrigerant
leak. To inspect the A/C evaporator for leaks, insert the leak detector probe into the drain tube opening or an air
outlet. A dye for R-134a is available to aid in leak detection. Use only DaimlerChrysler approved refrigerant dye.
RECOVERY/RECYCLING/EVACUATION/CHARGING HOSE– The center manifold hose (Yellow, or White, with
Black stripe) (3) is used to recover, evacuate, and charge the refrigerantsystem. When the low or high pressure
valves on the manifold gauge set are opened, the refrigerant in the system will escape through this hose.
HIGH PRESSURE GAUGE HOSE– The high pressure hose (Red with Black stripe) (4) attaches to the high side
service port. This service port is located on the A/C discharge line. On this model, an A/C pressure transducer is
installed on the high side service port. A/C high-side pressures can be read using a scan tool. Refer to 9 - Engine
Electrical Diagnostics for more information.
LOW PRESSURE GAUGE HOSE– The low pressure hose (Blue with Black stripe) (5) attaches to the low side
service port. This service port is located either on the top of the A/C accumulator or on the A/C suction line near the
accumulator, depending on engine application.
REFRIGERANT SYSTEM RECOVERY
WARNING: Refer to the applicable warnings and cautions for this system before performing the following
operation (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - WARNINGS) and (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - CAUTIONS). Failure to follow the warnings and cautions could result
in possible personal injury or death.
An R-134a refrigerant recovery/recycling/charging sta-
tion (1) that meets SAE standard J2210 must be used
to recover the refrigerant from the R-134a refrigerant
system. Refer to the operating instructions supplied by
the equipment manufacturer for the proper care and
use of this equipment.
REFRIGERANT SYSTEM EVACUATE
NOTE: Special effort must be used to prevent moisture from entering the A/Csystem oil. Moisture in the oil
is very difficult to remove and will cause a reliability problem with the compressor.
If an A/C compressor designed to use R-134a refrigerant is left open to the atmosphere for an extended period of
time. It is recommended that the refrigerant oil be drained and replaced with new oil or a new A/C compressor be
used. This will eliminate the possibility of contaminating the refrigerant system.
If the refrigerant system has been open to the atmosphere, it must be evacuated before the system can be filled.
Moisture and air mixed with the refrigerant will raise the compressor headpressure above acceptable operating
levels. This will reduce the performance of the A/C system and damage the A/C compressor. Moisture will boil at
near room temperature when exposed to vacuum. To evacuate the refrigerantsystem:
NOTE: When connecting the service equipment coupling to the line fitting,verify that the valve of the cou-
pling is fully closed. This will reduce the amount of effort required to make the connection.
1. Recover the refrigerant system (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD PRO-
CEDURE - REFRIGERANT SYSTEM RECOVERY).
2. Connect a suitable charging station, refrigerant recovery machine or amanifold gauge set with vacuum pump
and refrigerant recovery equipment (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - STANDARD
PROCEDURE - REFRIGERANT SYSTEM SERVICE EQUIPMENT).
3. Open the suction and discharge valves and start the vacuum pump. The vacuum pump should run a minimum of
45minutespriortochargetoeliminateall moisture in system. When the suction gauge reads to the lowest