1999 DODGE RAM relay

filter the refrigerant. The orifice tube is used to meter the flow of
liquid refrigerant into the evaporator core.
HIGH PRESSURE CUT-OUT SWITCH
High pressure cut-out switch is located on compressor
discharge line, near compressor. On Dakota and Ram Pickup, it is
connected in series with the clutch cycling pressure switch and
control panel, between ground and PCM.
On Durango, it is connected in series with the electronic
cycling clutch switch, low pressure cut-out switch and control panel,
between ground and PCM. PCM controls compressor clutch operation.
On all models, when discharge pressure reaches 450-490 psi
(31.6-34.5 kg/cm
), high pressure cut-out switch interrupts A/C
request signal to PCM. PCM de-energizes compressor clutch relay,
disengaging compressor clutch. When discharge pressure drops to 270-
330 psi (23.2-19 kg/cm
) switch will close, thus restoring A/C request
signal to PCM.
HIGH PRESSURE RELIEF VALVE
High pressure relief valve is located on compressor manifold.
Valve vents system pressure if pressure is greater than 500-600 psi
(35.1-42.2 kg/cm
). Valve will reset when pressure decreases to 400
psi (28.1 kg/cm).
LOW PRESSURE CUT-OUT SWITCH OPERATION
Durango
Low pressure cut-out switch is located on suction line near
firewall. It is connected in series with the electronic cycling clutch
switch, high pressure cut-out switch and control panel, between ground
and PCM. PCM controls compressor clutch operation.
When discharge pressure reaches 10 psi (.7 kg/cm
), switch
interrupts A/C request signal to PCM. PCM de-energizes compressor
clutch relay, disengaging compressor clutch. When discharge pressure
increases to 13-27 psi (.9-1.9 kg/cm
), switch will close thus
restoring A/C request signal to PCM.
ADJUSTMENTS
TEMPERATURE CONTROL CABLE ADJUSTMENT
Dakota & Durango
1) Ensure temperature control cable housing and core are
connected at both A/C-heater control panel and A/C-heater assembly.
Ensure A/C-heater control panel is installed.
2) Rotate temperature control knob so that knob pointer is at
12 o'clock position. Pull temperature control knob straight out from
A/C-heater control panel until perimeter of knob (not knob pointer)
protrudes about .25" (6 mm) from face of A/C-heater control panel.
3) Rotate temperature control knob clockwise so that knob
pointer is at one o'clock position. Push in on knob slightly and
continue rotating knob to its full clockwise stop. Place knob pointer
at a position about .32" (8 mm) beyond end of Red stripe. Release
knob. If knob is pointing at about .32" (8 mm) beyond end of Red
stripe, go to next step. If knob is not pointing at about .32" (8 mm)
beyond end of Red stripe, go back to step 2) and repeat adjustment
procedure.
4) Rotate temperature control knob counterclockwise so that
knob pointer is at 12 o'clock position. Push temperature control knob
straight into A/C-heater control panel until perimeter of knob (not

A/C SYSTEM PERFORMANCE PRESSURE SPECIFICATIONS (RAM PICKUP)








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Ambient Temp. High Side Low SideF (C) psi (kg/cm) psi (kg/cm)
70 (21) .............. 135-145 (9.5-10.2) ........ 35-40 (2.5-2\
.8)
80 (27) .............. 175-215 (12.3-15.1) ....... 40-50 (2.8-3\
.5)
90 (32) .............. 215-270 (15.1-19.0) ....... 50-60 (3.5-4\
.2)
100 (38) ............. 270-330 (19.0-23.2) ....... 60-70 (4.2-4\
.9)
110 (43) ............. 340-370 (23.9-26.0) ....... 70-80 (4.9-5\
.6)
120 (49) ............. 400-430 (28.1-30.2) ....... 85-90 (6.0-6\
.3)









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BLOWER MOTOR RELAY, HIGH SPEED BLOWER MOTOR RELAY &
COMPRESSOR CLUTCH RELAY
NOTE: Relays appear different, but testing procedures for blower
motor, high speed blower motor, and compressor clutch relays
are identical.
1) Front blower motor relay and compressor clutch relay are
located in Power Distribution Center (PDC). On Durango, high speed
blower motor relay is located in fuse/relay block under left side of
instrument panel.
2) Disconnect negative battery cable. Remove blower motor or
compressor clutch relay. Using an ohmmeter, check for continuity
between terminals No. 87A and 30 of relay. See Fig. 1 or 2. If
continuity does not exist, replace relay. If continuity exists, go to
next step.
3) Using an ohmmeter, check for continuity between terminals
No. 30 and 87 of relay. If continuity exists, replace relay. If
continuity does not exist, go to next step.
4) Measure resistance between terminals No. 85 and 86 of
relay. Reading should be 70-80 ohms. If reading is not as specified,
replace relay. If reading is as specified, go to next step.
5) Using jumper wires, connect battery voltage to terminal
No. 86 and ground terminal No. 85. See Fig. 1 or 2. Check that
continuity exists between terminals No. 30 and 87. Check that
continuity does not exist between terminals No. 87A and 30. If
continuity is not as specified, replace relay. If continuity is as
specified, relay is okay.
Fig. 1: Identifying Blower Motor Relay Terminals (Typical)
Courtesy of Chrysler Corp.

Fig. 2: Identifying Compressor Clutch Relay Terminals (Typical)
Courtesy of Chrysler Corp.
BLOWER MOTOR RESISTOR
1) Disconnect negative battery cable. Disconnect blower motor
resistor harness connector. Using an ohmmeter, check for continuity
between all 4 front blower motor resistor terminals, or 3 rear blower
motor resistor terminals. If continuity exists, go to next step. If
continuity does not exist, replace faulty blower motor resistor.
2) Check for open or short in circuits between blower motor
resistor and A/C-heater control panel. Also check for open or short in
wire between blower motor resistor and blower motor.
BLOWER MOTOR SWITCH
Front
1) Using a voltmeter, check underhood power distribution
center for battery voltage at fuse No. 5 (40-amp) on Dakota and
Durango, or fuse No. 5 (40-amp) on Ram Pickup. If battery voltage
exists, go to next step. If battery voltage does not exist, check for
open in Red wire between battery and underhood power distribution
center. If Red wire is okay, replace underhood power distribution
center.
2) Disconnect negative battery cable. Remove A/C-heater
control panel. See A/C-HEATER CONTROL PANEL R & I . Disconnect A/C-
heater control panel harness connector. Using an ohmmeter, check for
continuity between A/C-heater control panel harness connector terminal
No. 7 (Black wire on Dakota and Durango; Black/Orange on Ram Pickup)
and ground. If continuity exists, go to step 4).
3) If continuity does not exist, repair open in Black or
Black/Orange wire between A/C-heater control panel harness connector
terminal No. 7 and ground connector located at lower right corner of
instrument panel (Dakota and Durango) or behind center of instrument
panel (Ram Pickup).
4) Place mode control knob to any position except OFF. Using
an ohmmeter, check for continuity between A/C-heater control panel
connector terminal No. 7 and terminals No. 3, 4, 5, and 6 while
rotating blower motor switch. See Fig. 3.
5) If continuity does not exist at any terminal, replace
faulty A/C-heater control panel. If continuity exists as specified,
check for open in circuits between A/C-heater control panel and blower
motor resistor. Also check for an open in circuit between A/C-heater

control panel and blower motor.
Fig. 3: Identifying Blower Motor Switch Connector Terminals (Typical)\
Courtesy of Chrysler Corp.
Rear (Durango)
1) Disconnect negative battery cable. Remove rear blower
motor switch located in headliner. See BLOWER MOTOR SWITCH (REAR)
under REMOVAL & INSTALLATION. Disconnect rear blower motor switch
connector. Using an ohmmeter, check continuity between rear blower
motor switch connector Black wire and ground. If continuity exists, go
to next step. If continuity does not exist, repair open in Black wire
between rear blower motor switch connector and ground connector
located at left rear of vehicle body.
2) Place blower motor switch knob to any position except OFF.
Using an ohmmeter, check for continuity between rear blower motor
switch connector Black wire and Black/Light Blue wire, and
Black/Orange wire and Dark Green wire while rotating blower motor
switch.
3) If continuity does not exist at any terminal, replace
faulty blower motor switch. If continuity exists as specified, check
for open in circuits between blower motor switch and blower motor
resistor. Also check for an open in circuit between blower motor
switch connector and blower motor relay.
CLUTCH CYCLING PRESSURE SWITCH
Dakota & Ram Pickup
1) Locate clutch cycling pressure switch on side or top of
A/C accumulator. Ensure clutch cycling pressure switch is properly
installed on A/C accumulator fitting. Ensure system pressure is
correct. See A/C SYSTEM PERFORMANCE test.
2) Start and run engine with A/C on. If clutch cycles, turn
engine off and disconnect negative battery cable. Disconnect clutch
cycling pressure switch connector. Place a jumper wire across
terminals of clutch cycling pressure switch harness connector. Connect
negative battery cable. Connect manifold gauge set. Set A/C-heater


A/C -H EA TE R S YSTE M T R O UBLE S H O OTIN G

1999 D odge P ic ku p R 1500
1999 MANUAL A/C-HEATER SYSTEMS
Trouble Shooting - Cars & Trucks
CHRYSLER
Avenger, Breeze, Caravan, Cirrus, Concorde, Dakota, Durango,
Intrepid, LHS, Neon, Ram Pickup, Ram Van/Wagon, Sebring Convertible,
Sebring Coupe, Stratus, Town & Country, Voyager, 300M
A/C SYSTEM DIAGNOSIS
RAPID COMPRESSOR CLUTCH CYCLING
Some possible causes of rapid compressor clutch cycling,
clutch cycles 10 or more times per minute, include:
* Low refrigerant system charge.
* Faulty low pressure cycling clutch switch.
* Faulty PCM.
COMPRESSOR WILL NOT ENGAGE
Some possible causes of compressor not engaging with high and
low side system pressures equal include:
* No refrigerant in system.
* Faulty fuse.
* Faulty compressor clutch coil.
* Faulty compressor clutch relay.
* Faulty electronic cycling clutch switch.
* Improperly installed or faulty low pressure cycling clutch
switch.
* Faulty low pressure cut-off switch.
* Faulty high pressure cut-off switch.
* Faulty PCM.
* Faulty A/C-heater control panel.
TEMPERATURE IS TOO HIGH WITH A/C ON
Some possible causes of high temperature output at center
panel when A/C system pressure is normal include:
* Excessive oil charge in refrigerant.
* Temperature control cable improperly installed or faulty.
* Blend-air door inoperative, obstructed or sealing
improperly.
* Blend door actuator not calibrated.
LOW SIDE PRESSURE IS LOW-TO-NORMAL & HIGH SIDE PRESSURE IS
LOW
Some possible causes of low side system pressure being lower-
to-normal and high side system pressure being too low include:
* Low refrigerant system charge.
* Refrigerant flow through accumulator is restricted.
* Refrigerant flow through evaporator is restricted.
* Faulty compressor.
LOW SIDE PRESSURE IS HIGH-TO-NORMAL & HIGH SIDE PRESSURE IS

HIGH
Some possible causes of low side system pressure being high-
to-normal and high side system pressure being too high include:
* Condenser air flow restricted.
* Inoperative cooling fan.
* Faulty expansion valve.
* Refrigerant system overcharged.
* Air in refrigerant system.
* Engine overheating.
LOW SIDE PRESSURE IS HIGH & HIGH SIDE PRESSURE IS LOW
Some possible causes of low side system pressure being too
high and high side system pressure being too low include:
* Compressor belt is slipping.
* Fixed orifice tube not installed.
* Faulty compressor.
LOW SIDE PRESSURE IS LOW & HIGH SIDE PRESSURE IS HIGH
Some possible causes of low side system pressure being too
low and high side system pressure being too high include:
* Restricted refrigerant flow through refrigerant lines.
* Restricted refrigerant flow through expansion valve.
* Restricted refrigerant flow through fixed orifice tube.
* Restricted refrigerant flow through receiver-drier.
* Restricted refrigerant flow through condenser.
BLOWER MOTOR DIAGNOSIS
BLOWER MOTOR INOPERATIVE
Some possible causes of an inoperative blower motor include:
* Faulty fuse.
* Faulty blower motor feed circuit wire harness or
connectors.
* Faulty blower motor ground circuit wire harness or
connector.
* Faulty blower motor resistor.
* Faulty blower motor relay.
* Faulty blower motor switch.
* Faulty A/C-heater mode control switch.
* Faulty blower motor.
BLOWER NOT OPERATING IN ALL SPEEDS
Possible causes of the blower not operating in all speeds
include:
* Faulty fuse.
* Faulty blower motor feed circuit wire harness or
connectors.
* Faulty blower motor relay.
* Faulty blower motor resistor.
* Faulty blower motor switch.

CTM has remote keyless entry receiver and control logic incorporated.
COMPONENT TESTS
RELAYS
NOTE: Headlight relay may also be referred to as the security
relay. On Ram Pickup, the headlight relay is located in Power
Distribution Center (PDC) in engine compartment. On Ram Van
and Ram Wagon, the headlight relay is taped to headlight
switch harness. On Ram Pickup, the horn relay is located in
Power Distribution Center (PDC) in engine compartment. On Ram\
Van and Ram Wagon, the horn relay is located in junction
block under left side of instrument panel. For circuit
testing, see WIRING DIAGRAMS.
Headlight Relay & Horn Relay
Remove relay to be tested. Measure resistance between
appropriate relay terminals with relay de-energized and energized. See
RELAY TEST SPECIFICATIONS table. See Fig. 1. If continuity or
resistance is not as specified, replace relay.
RELAY TEST SPECIFICATIONS









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Terminals Condition
De-Energized
87A & 30 .............................................. Continuity
87 & 30 ............................................ No Continuity
85 & 86 .................................... 70-80 Ohms Resistance
Energized ( 1)
87 & 30 ............................................... Continuity
87A & 30 ........................................... No Continuity
( 1) - Apply position battery voltage to terminal No. 85 and ground
terminal No. 86.









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Fig. 1: Identifying Relay Connector Terminals
Courtesy of Chrysler Corp.
SYSTEM TESTS

Box (DRB) scan tool with appropriate cartridge for system
diagnosis. Other after-market scan tools may be used for
system diagnosis. The following procedure is for DRB scan
tool usage. Use scan tool manufacturer's instruction for
operating scan tool.
NOTE: Ensure battery is fully charged before proceeding with test.
1) Ensure ignition is off. Connect DRB to Data Link Connector
(DLC) located under driver's side of instrument panel. Using scan
tool, display all Diagnostic Trouble Codes (DTCs). Identify DTCs once
retrieved. See DIAGNOSTIC TROUBLE CODES (DTC) & DRB MESSAGES table.
2) If scan tool will not power up, check for loose cable
connections or faulty cable. If cable connections and cable are okay,
check voltage at DLC terminal No. 16. Voltage should be at least 11
volts. If voltage is not as specified, check wiring circuit and
necessary fuses. See WIRING DIAGRAMS.
3) If scan tool displays an error message, RAM TEST FAILURE,
CARTRIDGE ERROR, KEY PAD TEST FAILURE, or LOW OR HIGH BATTERY, this
indicates a scan tool failure.
4) If DTCs are displayed, perform appropriate test(s). See
DIAGNOSTIC TROUBLE CODES (DTC) & DRB MESSAGES table. If no DTCs are
displayed, see TROUBLE SHOOTING in appropriate AUTOMATIC TRANSMISSION
OVERHAUL article.
DIAGNOSTIC TROUBLE CODES (DTC) & DRB MESSAGES









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DTC DRB-III Scan Tool Message
P0711 .................. TRANS TEMP SENSOR, NO TEMP RISE AFTER START
P0712 ............................. TRANS TEMP SENSOR VOLTAGE TO LOW
P0713 ............................ TRANS TEMP SENSOR VOLTAGE TO HIGH
P0720 ..................... LOW OUTPUT SPEED SENSOR RPM ABOVE 15 MPH
P0740 .................... TORQ CONVERTER CLU, NO RPM DROP AT LOCKUP
P0743 ........ TORQUE CONVERTER CLUTCH SOLENOID/TRANS RELAY CIRCUITS
P0748 ........... GOVERNOR PRESSURE SOL CONTROL/TRANS RELAY CIRCUITS
P0751 ....................... OD SWITCH PRESSED (LO) MORE THAN 5 MIN\
P0753 ................ TRANS 3-4 SHIFT SOLENOID/TRANS RELAY CIRCUITS
P0783 ....................... 3-4 SHIFT SOL, NO RPM DROP @ 3-4 SHIFT
P1740 (1) .......................... TCC OR O/D SOLENOID PERFORMANCE
P1756 .................... GOV PRESS NOT EQUAL TO TARGET @ 15-20 PSI
P1757 ...................... GOV PRES ABOVE 3 PSI IN GEAR WITH 0 MPH
P1762 .................... GOV PRESS SEN OFFSET VOLTS TO LOW OR HIGH
P1763 ....................... GOVERNOR PRESSURE SENSOR VOLTS TO HIGH
P1763B ...................... GOVERNOR PRESSURE SENSOR VOLTS TO HIGH
P1764 ........................ GOVERNOR PRESSURE SENSOR VOLTS TO LOW
P1765 ..................... TRANS 12 VOLT SUPPLY RELAY CNTRL CIRCUIT
P1899 .......................... P/N SWITCH STUCK IN PARK OR ON GEAR
( 1) - BR body only.









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CLEARING DIAGNOSTIC TROUBLE CODES
After repairs have been performed, clear DTCs from PCM memory
using scan tool, following scan tool manufacturer's instructions.
NOTE: If malfunction is no longer present after DTC is stored in
PCM memory, the PCM will erase DTC after ignition has been
cycled at least 50 times. DTC may be cleared by using scan
tool. Follow scan tool manufacturer's instructions. DTCs may
also be cleared by disconnecting negative battery cable for a
period of time, but other vehicle control modules may also be