2001 DODGE RAM engine

A/C Diagnosis
Condition Possible Causes Correction
LOW SIDE PRESSURE
IS NORMAL OR
SLIGHTLY HIGH, AND
HIGH SIDE PRESSURE
IS TOO HIGH.1. Condenser air flow
restricted.1. Check the condenser for damaged fins, foreign objects
obstructing air flow through the condenser fins, and
missing or improperly installed air seals. Refer to Cooling
for more information on air seals. Clean, repair, or replace
components as required.
2. Inoperative cooling
fan.2. Refer to Cooling for more information. Test the cooling
fan and replace, if required.
3. Refrigerant system
overcharged.3. (Refer to Plumbing/Standard Procedure - Refrigerant
System Charge) in this group. Recover the refrigerant
from the refrigerant system. Charge the refrigerant
system to the proper level, if required.
4. Air in the refrigerant
system.4. (Refer to Plumbing/Diagnosis and Testing - Refrigerant
System Leaks) in this group. Test the refrigerant system
for leaks. Repair, evacuate and charge the refrigerant
system, if required.
5. Engine overheating. 5. Refer to Cooling for more information. Test the cooling
system and repair, if required.
LOW SIDE PRESSURE
IS TOO HIGH, AND
HIGH SIDE PRESSURE
IS TOO LOW.1. Accessory drive belt
slipping.1. Refer to Cooling for more information. Inspect the
accessory drive belt condition and tension. Tighten or
replace the accessory drive belt, if required.
2. A/C orifice tube not
installed.2. (Refer to Plumbing/A/C Orifice Tube/Diagnosis and
Testing) in this group. Replace the liquid line, if required.
3. Faulty a/c compressor. 3. (Refer to Plumbing/A/C Compressor/ Removal/
Installation) in this group. Replace the compressor, if
required.
LOW SIDE PRESSURE
IS TOO LOW, AND HIGH
SIDE PRESSURE IS
TOO HIGH.1. Restricted refrigerant
flow through the
refrigerant lines.1. (Refer to Plumbing/Caution - Refrigerant Hoses/Lines/
Tubes Precautions) in this group. Inspect the refrigerant
lines for kinks, tight bends or improper routing. Correct
the routing or replace the refrigerant line, if required.
2. Restricted refrigerant
flow through the a/c
orifice tube.2. (Refer to Plumbing/A/C Orifice Tube/Diagnosis and
Testing) in this group. Replace the liquid line, if required.
3. Restricted refrigerant
flow through the a/c
condenser.3. (Refer to Plumbing/A/C Condenser/ Removal/
Installation) in this group. Replace the restricted a/c
condenser, if required.
BR/BEHEATING & AIR CONDITIONING 24 - 5
HEATING & AIR CONDITIONING (Continued)

DIAGNOSIS AND TESTING - HEATER
PERFORMANCE
Before performing the following tests, refer to Cool-
ing for the procedures to check the engine coolant
level and flow, engine coolant reserve/recovery sys-
tem operation, accessory drive belt condition and ten-
sion, radiator air flow and the fan drive operation.
Also be certain that the accessory vacuum supply
line is connected at the engine vacuum source.
MAXIMUM HEATER OUTPUT
Engine coolant is delivered to the heater core
through two heater hoses. With the engine idling atnormal operating temperature, set the temperature
control knob in the full hot position, the mode control
switch knob in the floor position, and the blower
motor switch knob in the highest speed position.
Using a test thermometer, check the temperature of
the air being discharged at the HVAC housing floor
outlets. Compare the test thermometer reading to the
Temperature Reference chart.
Temperature Reference
Ambient Air Temperature15.5É C
(60É F)21.1É C
(70É F)26.6É C
(80É F)32.2É C
(90É F)
Minimum Air Temperature at
Floor Outlet62.2É C
(144É F)63.8É C
(147É F)65.5É C
(150É F)67.2É C
(153É F)
If the floor outlet air temperature is too low, refer
to Cooling to check the engine coolant temperature
specifications. Both of the heater hoses should be hot
to the touch. The coolant return heater hose should
be slightly cooler than the coolant supply heater
hose. If the return hose is much cooler than the sup-
ply hose, locate and repair the engine coolant flow
obstruction in the cooling system. Refer to Cooling
for the procedures.
An alternate method of checking heater perfor-
mance is to use a DRBIIItscan tool to monitor the
engine coolant temperature. The floor outlet air tem-
perature reading should be no more than 4.5É C (40É
F) lower than the engine coolant temperature read-
ing.
OBSTRUCTED COOLANT FLOW Possible loca-
tions or causes of obstructed coolant flow:
²Faulty water pump.
²Faulty thermostat.
²Pinched or kinked heater hoses.
²Improper heater hose routing.
²Plugged heater hoses or supply and return ports
at the cooling system connections.
²A plugged heater core.If proper coolant flow through the cooling system is
verified, and heater outlet air temperature is still
low, a mechanical problem may exist.
MECHANICAL PROBLEMS Possible locations or
causes of insufficient heat:
²An obstructed cowl air intake.
²Obstructed heater system outlets.
²A faulty, obstructed or improperly installed
blend door.
²A faulty blower system.
²A faulty a/c heater control.
TEMPERATURE CONTROL
If the heater outlet air temperature cannot be
adjusted with the temperature control knob on the
a/c heater control panel, the following could require
service:
²A faulty a/c heater control.
²A faulty blend door actuator.
²A faulty, obstructed or improperly installed
blend door.
²An obstructed cowl air intake.
²The engine cooling system.
24 - 6 HEATING & AIR CONDITIONINGBR/BE
HEATING & AIR CONDITIONING (Continued)

Heater Diagnosis
CONDITION POSSIBLE CAUSE CORRECTION
INSUFFICIENT HEATER
OUTPUT.1. Incorrect engine
coolant level.1. Check the engine coolant level. Refer to Cooling for
the procedures.
2. Air trapped in engine
cooling system.2. Check the operation of the coolant reserve/recovery
system. Refer to Cooling for the procedures.
3. Incorrect engine
coolant temperature.3. Check the performance and operation of the engine
cooling system including: thermostat, water pump, fan
drive, accessory drive belt, coolant flow (plugged radiator
or heater core, plugged or kinked coolant hoses), air flow
(missing or improperly installed radiator air seals or fan
shroud). Refer to Cooling for the procedures.
4. Blend door actuator
inoperative or defective.4. (Refer to Controls/Blend Door Actuator) in this group.
5. Blend door not
operating properly.5. Check for a damaged, obstructed or improperly
installed blend door or seals. (Refer to Controls/Blend
Door Actuator) in this group.
6. Insufficient air flow
through heater housing.6. Remove foreign material or obstructions from cowl air
intake.
7. Improper blower motor
operation.7. (Refer to Distribution/Blower Motor/ Diagnosis and
Testing) in this group.
STANDARD PROCEDURE - DIODE
REPLACEMENT
(1) Disconnect the battery.
(2) Locate the diode in the harness, and remove
the protective covering.
(3) Remove the diode from the harness, pay atten-
tion to the current flow direction (Fig. 3).(4) Remove the insulation from the wires in the
harness. Only remove enough insulation to solder in
the new diode.
(5) Install the new diode in the harness, making
sure current flow is correct. If necessary refer to the
appropriate wiring diagram for current flow.
(6) Solder the connection together using rosin core
type solder only.Do not use acid core solder.
(7) Tape the diode to the harness using electrical
tape making, sure the diode is completely sealed
from the elements.
(8) Re-connect the battery, and test affected sys-
tems.
Fig. 3 DIODE IDENTIFICATION
1 - CURRENT FLOW
2 - BAND AROUND DIODE INDICATES CURRENT FLOW
3 - DIODE AS SHOWN IN THE DIAGRAMS
BR/BEHEATING & AIR CONDITIONING 24 - 7
HEATING & AIR CONDITIONING (Continued)

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)

CONTROLS
DIAGNOSIS AND TESTING - VACUUM SYSTEM
Vacuum control is used to operate the mode doors
in the heater-only and HVAC housings. Testing of the
heater-only and a/c heater mode control switch oper-
ation will determine if the vacuum, electrical, and
mechanical controls are functioning. However, it is
possible that a vacuum control system that operates
perfectly at engine idle (high engine vacuum) may
not function properly at high engine speeds or loads
(low engine vacuum). This can be caused by leaks in
the vacuum system, or by a faulty or improperly
installed vacuum check valve.
A vacuum system test will help to identify the
source of poor vacuum system performance or vac-
uum system leaks. Before starting this test, stop the
engine and make certain that the problem is not a
disconnected vacuum supply tube at the engine vac-
uum source or the vacuum reservoir.
Use an adjustable vacuum test set (Special Tool
C-3707) and a suitable vacuum pump to test the
HVAC vacuum control system. With a finger placed
over the end of the vacuum test hose probe (Fig. 1),
adjust the bleed valve on the test set gauge to obtain
a vacuum of exactly 27 kPa (8 in. Hg.). Release and
block the end of the probe several times to verify that
the vacuum reading returns to the exact 27 kPa (8
in. Hg.) setting. Otherwise, a false reading will be
obtained during testing.
VACUUM CHECK VALVE
(1) Remove the vacuum check valve. On gasoline
engines, one valve is located in the vacuum supply
tube (black) at the intake manifold tap on the right
side of the engine. A second check valve is located
next to the tee fitting in the vacuum supply tube
(black) near the dash panel in the engine compart-
ment. On diesel engines, the vacuum check valve is
integral to the engine vacuum pump nipple and is
threaded into the vacuum pump. The vacuum check
valve must be removed in order to perform the fol-
lowing tests. (Refer to 24 - HEATING & AIR CONDI-
TIONING/CONTROLS/VACUUM CHECK VALVE -
REMOVAL)
(2) Connect the test set vacuum supply hose to the
a/c heater control side of the valve. When connected
to this side of the check valve, no vacuum should
pass and the test set gauge should return to the 27kPa (8 in. Hg.) setting. If OK, go to step Step 3. If
not OK, replace the faulty valve.
(3) Connect the test set vacuum supply hose to the
engine vacuum side of the valve. When connected to
this side of the check valve, vacuum should flow
through the valve without restriction. If not OK,
replace the faulty valve.
A/C HEATER CONTROLS
(1) Connect the test set vacuum probe to the
HVAC vacuum supply (black) tube in the engine com-
partment. Position the test set gauge so that it can
be viewed from the passenger compartment.
(2) Place the a/c heater mode control switch knob
to each mode position, one position at a time, and
pause after each selection. The test set gauge should
return to the 27 kPa (8 in. Hg.) setting shortly after
each selection is made. If not OK, a component or
vacuum line in the vacuum circuit of the selected
mode has a leak. See Locating Vacuum Leaks below.
CAUTION: Do not use lubricant on the switch ports
or in the holes in the plug, as lubricant will ruin the
vacuum valve in the switch. A drop of clean water
in the connector plug holes will help the connector
slide onto the switch ports.
Fig. 1 ADJUST VACUUM TEST BLEED VALVE
1 - VACUUM PUMP TOOL C-4289
2 - VACUUM TEST SET C-3707
3 - BLEED VALVE
4 - PROBE
24 - 10 CONTROLSBR/BE

A/C COMPRESSOR CLUTCH
DESCRIPTION
The compressor clutch assembly consists of a sta-
tionary electromagnetic coil, a hub bearing and pul-
ley assembly, and a clutch plate (Fig. 4). The
electromagnetic coil unit and the hub bearing and
pulley assembly are each retained on the nose of the
compressor front housing with snap rings. The clutch
plate is mounted to the compressor shaft and secured
with a nut.
OPERATION
The compressor clutch assembly provides the
means to engage and disengage the compressor from
the engine serpentine accessory drive belt. When the
clutch coil is energized, it magnetically draws the
clutch into contact with the pulley and drives the
compressor shaft. When the coil is not energized, the
pulley freewheels on the clutch hub bearing, which is
part of the pulley. The compressor clutch and coil are
the only serviced parts on the compressor.
The compressor clutch engagement is controlled by
several components: the a/c heater mode control
switch, the a/c low pressure switch, the a/c high pres-
sure switch, the compressor clutch relay, and the
Powertrain Control Module (PCM). The PCM may
delay compressor clutch engagement for up to thirty
seconds. Refer to Electronic Control Modules for
more information on the PCM controls.
DIAGNOSIS AND TESTING - A/C COMPRESSOR
CLUTCH COIL
For circuit descriptions and diagrams, (Refer to
Appropriate Wiring Information). The battery must
be fully-charged before performing the following
tests. Refer to Battery for more information.
(1) Connect an ammeter (0 to 10 ampere scale) in
series with the clutch coil terminal. Use a voltmeter
(0 to 20 volt scale) with clip-type leads for measuring
the voltage across the battery and the compressor
clutch coil.
(2) With the a/c heater mode control switch in any
A/C mode, and the blower motor switch in the lowest
speed position, start the engine and run it at normal
idle.
(3) The compressor clutch coil voltage should read
within 0.2 volts of the battery voltage. If there is
voltage at the clutch coil, but the reading is not
within 0.2 volts of the battery voltage, test the clutch
coil feed circuit for excessive voltage drop and repair
as required. If there is no voltage reading at the
clutch coil, use a DRB IIItscan tool and (Refer to
Appropriate Diagnostic Information) for testing of the
compressor clutch circuit. The following components
must be checked and repaired as required before you
can complete testing of the clutch coil:
²Fuses in the junction block and the Power Dis-
tribution Center (PDC)
²A/C Heater mode control switch
²Compressor clutch relay
²A/C High Pressure Switch
²A/C Low Pressure Switch
²Powertrain Control Module (PCM).
(4) The compressor clutch coil is acceptable if the
current draw measured at the clutch coil is 2.0 to 3.9
amperes with the electrical system voltage at 11.5 to
12.5 volts. This should only be checked with the work
area temperature at 21É C (70É F). If system voltage
is more than 12.5 volts, add electrical loads by turn-
ing on electrical accessories until the system voltage
drops below 12.5 volts.
(a) If the clutch coil current reading is four
amperes or more, the coil is shorted and should be
replaced.
(b) If the clutch coil current reading is zero, the
coil is open and should be replaced.
STANDARD PROCEDURE - A/C COMPRESSOR
CLUTCH BREAK-IN
After a new compressor clutch has been installed,
cycle the compressor clutch approximately twenty
times (five seconds on, then five seconds off). During
this procedure, set the A/C Heater control to the
Recirculation Mode, the blower motor switch in the
highest speed position, and the engine speed at 1500
to 2000 rpm. This procedure (burnishing) will seat
Fig. 4 COMPRESSOR CLUTCH - TYPICAL
1 - CLUTCH PLATE
2 - SHAFT KEY
3 - PULLEY
4 - COIL
5 - CLUTCH SHIMS
6 - SNAP RING
7 - SNAP RING
BR/BECONTROLS 24 - 13

the opposing friction surfaces and provide a higher
compressor clutch torque capability.
REMOVAL
The refrigerant system can remain fully-charged
during compressor clutch, pulley, or coil replacement.
The compressor clutch can be serviced in the vehicle.
(1) Disconnect and isolate the battery negative
cable.
(2) On models with the diesel engine option,
remove the compressor from the engine. Do not
remove the refrigerant lines or fittings. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/A/C
COMPRESSOR - REMOVAL)
(3) Unplug the compressor clutch coil wire harness
connector.
(4) Insert the two pins of the spanner wrench
(Special Tool 6462 in Kit 6460) into the holes of the
clutch plate. Hold the clutch plate stationary and
remove the hex nut (Fig. 5).
(5) Remove the clutch plate and clutch shims. On
models with the diesel engine option, a puller (Spe-
cial Tool 6461 in Kit 6460) is used to remove the
clutch plate (Fig. 6). This compressor also uses a
shaft key, which must be removed.
(6) Remove the external front housing snap ring
with snap ring pliers (Fig. 7).
(7) Install the lip of the rotor puller (Special Tool
C-6141-1 in Kit 6460) into the snap ring groove
exposed in Step 6, and install the shaft protector
(Special Tool C-6141-2 in Kit 6460) (Fig. 8).
(8) Install the puller through-bolts (Special Tool
C-6461) through the puller flange and into the jaws
of the rotor puller and tighten (Fig. 9). Turn the
puller center bolt clockwise until the rotor pulley is
free.(9) Remove the screw and retainer from the clutch
coil lead wire harness on the compressor front hous-
ing (Fig. 10).
(10) Remove the snap ring from the compressor
hub and remove the clutch field coil (Fig. 11). Slide
the clutch field coil off of the compressor hub.
Fig. 5 CLUTCH NUT REMOVE
1 - FRONT PLATE SPANNER
Fig. 6 CLUTCH PULLER - DIESEL MODELS
1 - FRONT PLATE
2 - PULLER
Fig. 7 EXTERNAL SNAP RING REMOVE
1 - EXTERNAL SNAP RING
24 - 14 CONTROLSBR/BE
A/C COMPRESSOR CLUTCH (Continued)

INSPECTION
Examine the friction surfaces of the clutch pulley
and the front plate for wear. The pulley and front
plate should be replaced if there is excessive wear or
scoring.
If the friction surfaces are oily, inspect the shaft
and nose area of the compressor for oil. Remove the
felt from the front cover. If the felt is saturated with
oil, the shaft seal is leaking and the compressor must
be replaced.
Check the clutch pulley bearing for roughness or
excessive leakage of grease. Replace the bearing, if
required.
INSTALLATION
(1) Install the clutch field coil and snap ring.
(2) Install the clutch coil lead wire harness retain-
ing clip on the compressor front housing and tighten
the retaining screw.
(3) Align the rotor assembly squarely on the front
compressor housing hub.
(4) Thread the handle (Special Tool 6464 in Kit
6460) into the driver (Special Tool 6143 in Kit 6460)
(Fig. 12).
(5) Place the driver tool assembly into the bearing
cavity on the rotor. Make certain the outer edge of
the tool rests firmly on the rotor bearing inner race
(Fig. 13).
(6) Tap the end of the driver while guiding the
rotor to prevent binding. Tap until the rotor bottoms
against the compressor front housing hub. Listen for
a distinct change of sound during the tapping pro-
cess, to indicate the bottoming of the rotor.(7) Install the external front rotor snap ring with
snap ring pliers. The bevel side of the snap ring must
be facing outward. Press the snap ring to make sure
it is properly seated in the groove.
CAUTION: If the snap ring is not fully seated in the
groove it will vibrate out, resulting in a clutch fail-
ure and severe damage to the front housing of the
compressor.
(8) Install the original clutch shims on the com-
pressor shaft.
(9) Install the clutch plate. On models with the
diesel engine option, install the shaft key. Use the
shaft protector (Special Tool 6141-2 in Kit 6460) to
install the clutch plate on the compressor shaft (Fig.
14). Tap the clutch plate over the compressor shaft
until it has bottomed against the clutch shims. Lis-
ten for a distinct change of sound during the tapping
process, to indicate the bottoming of the clutch plate.
(10) Install the compressor shaft hex nut. Tighten
the nut to 14.4 N´m (10.5 ft. lbs.).
(11) Check the clutch air gap with a feeler gauge
(Fig. 15). If the air gap does not meet the specifica-
tion, add or subtract shims as required. The air gap
specification is 0.41 to 0.79 millimeter (0.016 to 0.031
inch). If the air gap is not consistent around the cir-
cumference of the clutch, lightly pry up at the mini-
mum variations. Lightly tap down at the points of
maximum variation.
Fig. 12 ROTOR INSTALLER SET
Fig. 13 ROTOR INSTALL
24 - 16 CONTROLSBR/BE
A/C COMPRESSOR CLUTCH (Continued)