2001 DODGE RAM cooling

SPECIFICATIONS
A/C APPLICATION TABLE
Item Description Notes
Vehicle BR/BE - Ram Pickup
System R134a w/orifice tube
Compressor Sanden SD7H15 SP-20 PAG
oil
Freeze±up
ControlA/C Low Pressure
Switchaccumulator
mounted
Low psi
Controlopens < 22-24 psi
resets > 37-43 psi
High psi
Controlswitch - opens > 450
- 490 psi, resets <
270 - 330 psimounted on
discharge
line, near
compressor
A/C Heater
Control Headmanual type
Mode Door vacuum actuatorItem Description Notes
Blend Door electric actuator
Recirculation
Doorvacuum actuator
Blower Motor hardwired to control
headresistor block
Cooling Fan viscous fan
Clutch
Control relay PCM
Draw 2 - 3.9 amps @ 12V60.5V @
70É F
Gap 0.0169- 0.0319
DRB IIIT
Reads TPS, RPM, A/C
switch test
Actuators clutch relay
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
A/C COMPRESSOR CLUTCH PLATE NUT 14.4 10.5 -
A/C COMPRESOR LINE MANIFOLD
FASTENER22 - 200
A/C COMPRESSOR TO MOUNTING
BRACKET BOLTS24 - 210
ACCUMULATOR RETAINING BAND 4.5 - 40
BLOWER MOTOR SCREWS 2.2 - 20
CHECK VALVE AND NIPPLE UNIT (DIESEL) 24 18 -
CONDENSER MOUNTING SCREWS/NUTS 10.5 - 95
DISCHARGE LINE TO CONDENSER
FASTENER20 - 180
DOOR ACTUATOR SCREWS 2.2 - 20
HVAC HOUSING SCREWS 2.2 - 20
HVAC HOUSING TO DASH PANEL NUTS
(ENGINE SIDE)7-60
HVAC HOUSING TO DASH PANEL NUTS
(PASSENGER COMPARTMENT SIDE)4.5 - 40
24 - 8 HEATING & AIR CONDITIONINGBR/BE
HEATING & AIR CONDITIONING (Continued)

tom of the a/c heater control panel. Refer to Heated
Mirrors for more information on this feature.
The heater-only or a/c heater control panel cannot
be repaired. If faulty or damaged, the entire unit
must be replaced. The control knobs and the illumi-
nation lamps are available for service replacement.
DIAGNOSIS AND TESTING - A/C HEATER
CONTROL
Satisfactory heater and air conditioner perfor-
mance depends upon proper operation and adjust-
ment of all operating controls and refrigeration
system components. For circuit descriptions and dia-
grams, (Refer to Appropriate Wiring Information).
These inspections, tests, and adjustments should be
used to locate the cause of a malfunction.
Operation must be tested as described in the fol-
lowing sequence:
(1) Inspect and adjust the serpentine drive belt.
Refer to Cooling for the procedures.
(2) Start the engine and hold the idle speed at
1,300 rpm.
(3) On vehicles with air conditioning, turn the
temperature control knob to the extreme counter-
clockwise (Cool) position, and set the mode control
switch knob to the Bi-Level (A/C) position. The out-
side (recirculation) air door should be open to outside
air. If not OK, (Refer to 24 - HEATING & AIR CON-
DITIONING/CONTROLS - DIAGNOSIS AND TEST-
ING - VACUUM SYSTEM).
(4) Open the vehicle windows. Test the blower
motor operation in all speeds. If not OK, (Refer to 24
- HEATING & AIR CONDITIONING/DISTRIBU-
TION/BLOWER MOTOR - DIAGNOSIS AND TEST-
ING).
(5) On vehicles with air conditioning, the compres-
sor should be running and the air conditioning sys-
tem in operation unless the ambient air temperature
is below about -1É C (30É F). If not OK, (Refer to 24 -
HEATING & AIR CONDITIONING - DIAGNOSIS
AND TESTING - A/C PERFORMANCE).
(6) Check the mode control switch operation. The
heater and air conditioner systems should respond as
described in the owner's manual in the vehicle glove
box to each mode selected. Reduce the engine speed
to normal idle. The vacuum will be high at low idle
and the vacuum actuators should respond quickly. If
not OK, (Refer to 24 - HEATING & AIR CONDI-
TIONING/CONTROLS - DIAGNOSIS AND TEST-
ING - VACUUM SYSTEM).
(7) If the vacuum tests, and the electrical compo-
nent and circuit tests reveal no problems, disassem-
ble the HVAC housing to inspect for mechanical
misalignment or binding of the mode doors. (Refer to
24 - HEATING & AIR CONDITIONING/DISTRIBU-
TION/HVAC HOUSING - DISASSEMBLY)
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Reach under the instrument panel near the
driver side of the floor panel transmission tunnel and
unplug the a/c heater control to HVAC housing vac-
uum harness connector.
(3) While still reaching under the instrument
panel, disengage the retainer on the a/c heater con-
trol half of the vacuum harness from the hole in the
center distribution duct (Fig. 18).
(4) Remove the cluster bezel from the instrument
panel. Refer to Instrument Panel System for the pro-
cedures.
Fig. 18 A/C HEATER CONTROL VACUUM HARNESS
ROUTING
1 - A/C HEATER CONTROL VACUUM HARNESS
2 - REINFORCEMENT
3 - RETAINER
4 - CENTER DISTRIBUTION DUCT
BR/BECONTROLS 24 - 19
A/C HEATER CONTROL (Continued)

DIAGNOSIS AND TESTING - BLOWER MOTOR
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPT-
ING ANY STEERING WHEEL, STEERING COLUMN, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. DISCONNECT AND ISOLATE THE BATTERY
NEGATIVE (GROUND) CABLE, THEN WAIT TWO MIN-
UTES FOR THE AIRBAG SYSTEM CAPACITOR TO DIS-
CHARGE 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 AN ACCIDENTAL AIRBAG DEPLOYMENT AND POS-
SIBLE PERSONAL INJURY.
For circuit descriptions and diagrams, (Refer to
Appropriate Wiring Information). Possible causes of
an inoperative blower motor include:
²Faulty fuse
²Faulty blower motor circuit wiring or wire har-
ness connectors
²Faulty blower motor resistor
²Faulty blower motor relay
²Faulty blower motor switch
²Faulty a/c heater mode control switch
²Faulty blower motor.
Possible causes of the blower motor not operating
in all speeds include:
²Faulty fuse
²Faulty blower motor switch
²Faulty blower motor resistor
²Faulty blower motor relay
²Faulty blower motor circuit wiring or wire har-
ness connectors.
VIBRATION
Possible causes of blower motor vibration include:
²Improper blower motor mounting
²Improper blower wheel mounting
²Blower wheel out of balance or deformed
²Blower motor faulty.
NOISE
To verify that the blower is the source of the noise,
unplug the blower motor wire harness connector and
operate the HVAC system. If the noise goes away,
possible causes include:
²Foreign material in the HVAC housing
²Improper blower motor mounting
²Improper blower wheel mounting
²Blower motor faulty.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.(2) Disconnect the blower motor cooling tube from
the nipple on the blower motor housing (Fig. 3).
(3) Disengage the blower motor wire harness from
the wire harness retainer.
(4) Unplug the blower motor wire harness connec-
tor from the HVAC housing wire harness.
(5) Remove the three screws that secure the
blower motor and blower wheel assembly to the
HVAC housing.
(6) Lower the blower motor and wheel assembly,
and cover, from the HVAC housing.
(7)
Remove the blower wheel retainer clip and
remove the wheel from the blower motor shaft (Fig. 4).
INSTALLATION
(1) If installing the blower motor wheel only, press
the blower wheel hub onto the blower motor shaft.
Be sure the flat on the blower motor shaft is indexed
to the flat on the inside of the blower wheel hub.
(2) Install the retainer clip over the blower wheel
hub. The ears of the retainer clip must be indexed
over the flats on the blower motor shaft and blower
wheel hub.
(3) Be certain that the blower motor seal is
installed on the blower motor housing (Fig. 5).
(4) Install the blower motor and wheel assembly,
and cover in the HVAC housing with three mounting
screws. Tighten the mounting screws to 2.2 N´m (20
in. lbs.).
Fig. 3 BLOWER MOTOR REMOVE/INSTALL
1 - BLOWER MOTOR HOUSING
2 - COOLING TUBE
3 - ELECTRICAL CONNECTOR
BR/BEDISTRIBUTION 24 - 33
BLOWER MOTOR (Continued)

(5) Plug the blower motor wire harness connector
into the HVAC housing wire harness.
(6) Install the blower motor wire harness into the
wire harness retainer.
(7) Connect the blower motor cooling tube to the
nipple on the blower motor housing.
(8) Connect the battery negative cable.
DEFROSTER DUCTS
REMOVAL - DEFROSTER AND DEMISTER
DUCTS
The defroster duct and the main demister duct are
a single molded plastic unit. The defroster outletgrilles are heat-staked to the defroster outlets and
cannot be serviced separately. The demister tubes on
each end of the main demister duct are only serviced
in the instrument panel assembly.
(1) Remove the instrument panel top cover from
the instrument panel. Refer to Instrument System
for the procedures.
(2) Remove the screws that secure the defroster
and demister ducts to the instrument panel brackets
(Fig. 6).
Fig. 5 BLOWER MOTOR SEAL
1 - BLOWER MOTOR SEAL
Fig. 6 DEFROSTER AND DEMISTER DUCT
1 - DEMISTER TUBE
2 - INSTRUMENT PANEL TOP COVER3 - BRACKETS
4 - DEFROSTER AND DEMISTER DUCT
Fig. 4 BLOWER MOTOR WHEEL REMOVE/INSTALL
1 - BLOWER MOTOR WHEEL
2 - RETAINER CLIP
24 - 34 DISTRIBUTIONBR/BE
BLOWER MOTOR (Continued)

(5) Remove the accumulator. (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING/ACCU-
MULATOR - REMOVAL) Install plugs in, or tape
over all of the opened refrigerant line fittings.
(6) Drain the engine cooling system. Refer to Cool-
ing for the procedures.
(7)
Disconnect the heater hoses from the heater core
tubes. Refer to Cooling for the procedures. Install plugs
in, or tape over the opened heater core tubes.
(8) Remove the Powertrain Control Module (PCM)
from the dash panel and set it aside, but do not
unplug the PCM wire harness connectors. Refer to
Electronic Control Modules for the procedures.
(9) Remove the nuts from the HVAC housing
mounting studs on the engine compartment side of
the dash panel.
(10) Remove the nuts that secure the HVAC hous-
ing to the mounting studs on the passenger compart-
ment side of the dash panel (Fig. 8).
(11) Pull the HVAC housing rearward far enough
for the mounting studs and the evaporator conden-
sate drain tube to clear the dash panel holes.
(12) Remove the HVAC housing from the vehicle.
REMOVAL - HVAC HOUSING INLET BAFFLE
(1) Remove the HVAC housing from the vehicle.
(Refer to 24 - HEATING & AIR CONDITIONING/
DISTRIBUTION/HVAC HOUSING - REMOVAL)
(2) Slide the HVAC housing inlet baffle (Fig. 9) all
the way to one side of the cowl plenum opening.
(3)
Pull downwards sharply and firmly on the oppo-
site side of the HVAC housing inlet baffle to disengage
the snap features from the cowl plenum opening.
(4) Remove the HVAC housing inlet baffle from the
cowl plenum panel.
DISASSEMBLY
(1) Place the HVAC housing upside down on a
work bench.
(2) Remove the screw that secures the floor duct to
the bottom of the HVAC housing and slide the floor
duct off of the center heat duct adaptor.
(3) Unsnap the center heat duct adaptor from the
bottom of the HVAC housing and remove the screw
that was hidden by the adaptor.
(4) Remove the remaining screws on the bottom of
the HVAC housing that secure the two housing
halves together.
(5) Place the HVAC housing right side up on the
work bench.
(6) Separate the top half of the HVAC housing
from the bottom half and set it aside.
ASSEMBLY
(1) Position the top half of the HVAC housing over
the bottom half. Be certain that the mode door pivot
pins are properly inserted in their pivot holes.
(2) Place the HVAC housing upside down on the
work bench.
(3)
Install and tighten the screws on the bottom of
the HVAC housing that secure the two housing halves
together. Tighten the screws to 2.2 N´m (20 in. lbs.).
(4) Snap the center heat duct adaptor onto the bot-
tom of the HVAC housing.
(5) Slide the floor duct onto the center heat duct
adaptor and secure it with a screw to the bottom of
the HVAC housing. Tighten the mounting screw to
2.2 N´m (20 in. lbs.).
Fig. 8 HVAC HOUSING REMOVE/INSTALL
1 - BODY ASSEMBLY
2 - HVAC HOUSING
Fig. 9 HVAC HOUSING INLET BAFFLE REMOVE/
INSTALL
1 - RIGHT A-PILLAR
2 - INLET BAFFLE
3 - COWL PLENUM OPENING
24 - 36 DISTRIBUTIONBR/BE
HVAC HOUSING (Continued)

INSTALLATION
(1) Position the HVAC housing to the dash panel.
Be certain that the evaporator condensate drain tube
and the housing mounting studs are inserted into
their correct mounting holes.
(2) Install the nuts that secure the HVAC housing
to the mounting studs on the passenger compartment
side of the dash panel. Tighten the nuts to 4.5 N´m
(40 in. lbs.).
(3)
Install and tighten the nuts onto the HVAC hous-
ing mounting studs on the engine compartment side of
the dash panel. Tighten the nuts to 7 N´m (60 in. lbs.).
(4) Unplug or remove the tape from the heater
core tubes. Connect the heater hoses to the heater
core tubes and fill the engine cooling system. Refer
Cooling for the procedures.
(5)
If the vehicle is not equipped with air condition-
ing, go to Step 10. If the vehicle is equipped with air
conditioning, install the accumulator. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/ACCU-
MULATOR - INSTALLATION) Connect the accumulator
inlet tube coupler to the evaporator outlet tube. (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING
- STANDARD PROCEDURE - A/C LINE COUPLERS)
(6)Unplug or remove the tape from the liquid line
and the evaporator inlet tube fittings. Connect the liq-
uid line coupler to the evaporator inlet tube. (Refer to
24 - HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - A/C LINE COUPLERS)
(7) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)
(8) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
(9) Reinstall the PCM to the dash panel. Refer to
Electronic Control Modules for the procedures.
(10) Reinstall the instrument panel in the vehicle.
Refer to Instrument Panel System for the procedures.
(11) Connect the battery negative cable.
(12) Start the engine and check for proper opera-
tion of the heating and air conditioning systems.
INSTALLATION - HVAC HOUSING INLET
BAFFLE
(1) Install the HVAC housing inlet baffle in the
cowl plenum panel.
(2) Slide the HVAC housing inlet baffle to engage
the snap features.
(3) Make certain that the snap features on each
side of the adapter are fully engaged with the sides
of the plenum panel opening. This must be a water
tight connection to prevent leaks.(4) Install the HVAC housing in the vehicle. (Refer
to 24 - HEATING & AIR CONDITIONING/DISTRI-
BUTION/HVAC HOUSING - INSTALLATION)
INSTRUMENT PANEL
DEMISTER DUCTS
REMOVAL
The defroster duct and the main demister duct are
a single molded plastic unit. The defroster outlet
grilles are heat-staked to the defroster outlets and
cannot be serviced separately. The demister tubes on
each end of the main demister duct are only serviced
in the instrument panel assembly. (Refer to 24 -
HEATING & AIR CONDITIONING/DISTRIBUTION/
DEFROSTER DUCTS - REMOVAL)
INSTRUMENT PANEL DUCTS
REMOVAL
The panel and center distribution ducts (Fig. 10)
are only serviced as part of the instrument panel
assembly. Refer to Instrument Panel System for the
service procedures.
Fig. 10 PANEL AND CENTER DISTRIBUTION DUCTS
1 - BRACKET
2 - SCREW
3 - CENTER DISTRIBUTION DUCT
4 - SCREW
5 - PANEL DUCTS
BR/BEDISTRIBUTION 24 - 37
HVAC HOUSING (Continued)

The refrigerant system will remain chemically sta-
ble as long as pure, moisture-free R-134a refrigerant
and refrigerant oil is used. Dirt, moisture, or air can
upset this chemical stability. Operational troubles or
serious damage can occur if foreign material is
present in the refrigerant system.
When it is necessary to open the refrigerant sys-
tem, have everything needed to service the system
ready. The refrigerant system should not be left open
to the atmosphere any longer than necessary. Cap or
plug all lines and fittings as soon as they are opened
to prevent the entrance of dirt and moisture. All lines
and components in parts stock should be capped or
sealed until they are to be installed.
All tools, including the refrigerant recycling equip-
ment, the manifold gauge set, and test hoses should
be kept clean and dry. All tools and equipment must
be designed for R-134a refrigerant.
DIAGNOSIS AND TESTING - REFRIGERANT
SYSTEM LEAKS
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
If the air conditioning system is not cooling prop-
erly, determine if the refrigerant system is fully-
charged. (Refer to 24 - HEATING & AIR
CONDITIONING - DIAGNOSIS AND TESTING -
A/C PERFORMANCE) If the refrigerant system is
low or empty; a leak at a refrigerant line, connector
fitting, component, or component seal is likely.
An electronic leak detector designed for R-134a
refrigerant, or a fluorescent R-134a leak detection
dye and a black light are recommended for locating
and confirming refrigerant system leaks. Refer to the
operating instructions supplied by the equipment
manufacturer for proper care and use of this equip-
ment.
An oily residue on or near refrigerant system lines,
connector fittings, components, or component seals
can indicate the general location of a possible refrig-
erant leak. However, the exact leak location should
be confirmed with an electronic leak detector prior to
component repair or replacement.
To detect a leak in the refrigerant system with an
electronic leak detector, perform one of the following
procedures:
SYSTEM EMPTY
(1) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)
(2) Connect and dispense 0.283 kilograms (0.625
pounds or 10 ounces) of R-134a refrigerant into the
evacuated refrigerant system. (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - STAN-
DARD PROCEDURE - REFRIGERANT SYSTEM
CHARGE)
(3) Position the vehicle in a wind-free work area.
This will aid in detecting small leaks.
(4) With the engine not running, use a electronic
R-134a leak detector and search for leaks. Because
R-134a refrigerant is heavier than air, the leak detec-
tor probe should be moved slowly along the bottom
side of all refrigerant lines, connector fittings and
components.
(5) To inspect the evaporator coil for leaks, insert
the electronic leak detector probe into the center
instrument panel outlet. Set the blower motor switch
to the lowest speed position, and the mode control
switch in the recirculation mode.
SYSTEM LOW
(1) Position the vehicle in a wind-free work area.
This will aid in detecting small leaks.
(2) Bring the refrigerant system up to operating
temperature and pressure. This is done by allowing
the engine to run with the air conditioning system
turned on for five minutes.
(3) With the engine not running, use a electronic
R-134a leak detector and search for leaks. Because
R-134a refrigerant is heavier than air, the leak detec-
tor probe should be moved slowly along the bottom
side of all refrigerant lines, connector fittings and
components.
(4) To inspect the evaporator coil for leaks, insert
the electronic leak detector probe into the center
instrument panel outlet. Set the blower motor switch
to the lowest speed position, and the mode control
switch in the recirculation mode.
STANDARD PROCEDURE - A/C LINE
COUPLERS
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
REMOVAL
(1) Recover the refrigerant from the refrigerant
system. (Refer to 24 - HEATING & AIR CONDI-
BR/BEPLUMBING 24 - 43
PLUMBING (Continued)

STANDARD PROCEDURE - REFRIGERANT
SYSTEM CHARGE
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
After the refrigerant system has been tested for
leaks and evacuated, a refrigerant charge can be
injected into the system. (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - SPECIFICA-
TIONS - CHARGE CAPACITY)
A R-134a refrigerant recovery/recycling/charging
station that meets SAE Standard J2210 must be
used to charge the refrigerant system with R-134a
refrigerant. Refer to the operating instructions sup-
plied by the equipment manufacturer for proper care
and use of this equipment.
SPECIFICATIONS
SPECIFICATIONS
The R-134a refrigerant system charge capacity for
this vehicle is: 0.907 kilograms (32 ounces).
A/C COMPRESSOR
DESCRIPTION - A/C COMPRESSOR
The air conditioning system uses a Sanden
SD7H15 seven cylinder, reciprocating wobble plate-
type compressor on all models. This compressor has a
fixed displacement of 150 cubic centimeters (9.375
cubic inches), and has both the suction and discharge
ports located on the cylinder head. A label identifying
the use of R-134a refrigerant is located on the com-
pressor.
DESCRIPTION - HIGH PRESSURE RELIEF
VALVE
A high pressure relief valve is located on the com-
pressor cylinder head, which is at the rear of the
compressor. This mechanical valve is designed to
vent refrigerant from the system to protect against
damage to the compressor and other system compo-
nents, caused by condenser air flow restriction or an
overcharge of refrigerant.
OPERATION - A/C COMPRESSOR
The compressor is driven by the engine through an
electric clutch, drive pulley and belt arrangement.
The compressor is lubricated by refrigerant oil that iscirculated throughout the refrigerant system with the
refrigerant.
The compressor draws in low-pressure refrigerant
vapor from the evaporator through its suction port. It
then compresses the refrigerant into a high-pressure,
high-temperature refrigerant vapor, which is then
pumped to the condenser through the compressor dis-
charge port.
The compressor cannot be repaired. If faulty or
damaged, the entire compressor assembly must be
replaced. The compressor clutch, pulley and clutch
coil are available for service.
OPERATION - HIGH PRESSURE RELIEF VALVE
The high pressure relief valve vents the system
when a discharge pressure of 3445 to 4135 kPa (500
to 600 psi) or above is reached. The valve closes with
a minimum discharge pressure of 2756 kPa (400 psi)
is reached.
The high pressure relief valve vents only enough
refrigerant to reduce the system pressure, and then
re-seats itself. The majority of the refrigerant is con-
served in the system. If the valve vents refrigerant, it
does not mean the valve is faulty.
The high pressure relief valve is a factory-cali-
brated unit. The valve cannot be adjusted or
repaired, and must not be removed or otherwise dis-
turbed. The valve is only serviced as a part of the
compressor assembly.
DIAGNOSIS AND TESTING - A/C COMPRESSOR
When investigating an air conditioning related
noise, you must first know the conditions under
which the noise occurs. These conditions include:
weather, vehicle speed, transmission in gear or neu-
tral, engine speed, engine temperature, and any
other special conditions. Noises that develop during
air conditioning operation can often be misleading.
For example: What sounds like a failed front bearing
or connecting rod, may be caused by loose bolts, nuts,
mounting brackets, or a loose compressor clutch
assembly.
Drive belts are speed sensitive. At different engine
speeds and depending upon belt tension, belts can
develop noises that are mistaken for a compressor
noise. Improper belt tension can cause a misleading
noise when the compressor clutch is engaged, which
may not occur when the compressor clutch is disen-
gaged. Check the serpentine drive belt condition and
tension as described in Cooling before beginning this
procedure.
(1) Select a quiet area for testing. Duplicate the
complaint conditions as much as possible. Switch the
compressor on and off several times to clearly iden-
tify the compressor noise. Listen to the compressor
while the clutch is engaged and disengaged. Probe
24 - 46 PLUMBINGBR/BE
PLUMBING (Continued)