DODGE RAM 1999 Service Repair Manual

REFILLING
To prevent air from being trapped in engine block, engine
should be running when refilling cooling system. After system is full,
continue running engine until thermostat is open, then recheck fill
level. Do not overfill system.
TESTING
THERMOSTAT
1) Visually inspect thermostat for corrosion and proper
sealing of valve and seat. If okay, suspend thermostat and thermometer
in a 50/50 mixture of coolant and water. See Fig. 1. Do not allow
thermostat or thermometer to touch bottom of container. Heat water
until thermostat just begins to open.
2) Read temperature on thermometer. This is the initial
opening temperature and should be within specification. Continue
heating water until thermostat is fully open and note temperature.
This is the fully opened temperature. If either reading is not to
specification, replace thermostat.
Fig. 1: Testing Thermostat in Anti-Freeze/Water Solution
PRESSURE TESTING
A pressure tester is used to check both radiator cap and

complete cooling system. Test components as follows, following tool
manufacturer's instructions.
Radiator Cap
Visually inspect radiator cap, then dip cap into water and
connect to tester. Pump tester to bring pressure to upper limit of cap
specification. If cap fails to hold pressure, replace cap.
Fig. 2: Testing Radiator Pressure Cap
Cooling System
1) With engine off, wipe radiator filler neck seat clean.
Fill radiator to correct level. Attach tester to radiator and pump
until pressure is at upper level of radiator rating.
2) If pressure drops, inspect for external leaks. If no leaks
are apparent, detach tester and run engine until normal operating
temperature is reached. Reattach tester and observe. If pressure
builds up immediately, a possible leak exists from a faulty head
gasket or crack in head or block.
NOTE: Pressure may build up quickly. Release any excess pressure
or cooling system damage may result.
3) If there is no immediate pressure build up, pump tester to
within system pressure range (on radiator cap). Vibration of gauge
pointer indicates compression or combustion leak into cooling system.
Isolate leak by shorting each spark plug wire to cylinder block. Gauge
pointer should stop or decrease vibration when leaking cylinder is
shorted.

HEA TE R S YSTE M

1999 D odge P ic ku p R 1500
1999 HEATER SYSTEMS
RWD Trucks & Vans
CHRYSLER
Dakota, Durango, Ram Pickup, Ram Van/Wagon
DESCRIPTION
All models use a blend-air system. Outside air enters heater
through cowl opening and passes through a plenum chamber to heater
core. Blend air door in heater housing controls temperature by either
directing air through or around heater core. Air flow is then directed
through dash panel to air distribution duct in passenger compartment.
On Durango, air taken from the front heater system is fed
back through an air duct into the center console. At the rear of the
center console, passengers can operate a 3 mode switch to adjust air
flow. Temperature and blower speeds are controlled by the front heater
control panel.
WARNING: To avoid injury from accidental air bag deployment, read and
carefully follow all SERVICE PRECAUTIONS and DISABLING &
ACTIVATING AIR BAG SYSTEM procedures in AIR BAG SYSTEM SAFETY
article.
OPERATION
HEATER CONTROL PANEL
Blower Motor Switch
Fan speed is controlled with a rotary blower motor switch.
There are 4 different fan speed settings: one low speed, 2 medium
speeds, and one high speed.
Mode Control Knob
A rotary mode switch is used to control air flow. There are 5
different modes of operation: panel, floor/panel, floor,
floor/defrost, and defrost.
Temperature Control Knob
Rotary control knob determines discharge air temperature by
positioning blend/air door. On Dakota and Durango, temperature blend-
air door is cable operated. On Ram Pickup and Ram Van/Wagon,
temperature blend-air door is electrically operated. When a hot
temperature is selected, all air flows through heater core.
ADJUSTMENTS
TEMPERATURE CONTROL CABLE ADJUSTMENT
Dakota & Durango
1) Ensure temperature control cable housing and core are
connected at both heater control panel and heater assembly. Ensure
heater control panel is properly installed.
2) Rotate temperature control knob so that knob pointer is at
12 o'clock position. Pull temperature control knob straight out from
heater control panel until perimeter of knob (not knob pointer)
protrudes about .25" (6 mm) from face of 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 heater control panel until perimeter of knob (not knob
pointer) is flush with base of heater control panel.
5) Rotate temperature control knob to its full clockwise
stop. Release knob. Knob pointer should be aimed at end of Red stripe.
If knob is pointed at end of Red stripe, go to next step. If knob is
not pointed at end of Red stripe, go back to step 2) and repeat
adjustment procedure.
6) Rotate temperature control knob to its full
counterclockwise stop. Release knob. If knob springs back, self-
adjuster clip securing temperature control cable to blend-air door
lever is improperly installed. See TEMPERATURE CONTROL CABLE R & I
under REMOVAL & INSTALLATION. If knob does not springs back,
temperature control cable adjustment is complete.
TROUBLE SHOOTING
HEATER PERFORMANCE
Check cooling system. Check serpentine drive belt tension.
Check radiator and radiator fan operation. Ensure that accessory
vacuum supply line is connected at power brake booster (Dakota) or
engine vacuum source (except Dakota).
TESTING
WARNING: To avoid injury from accidental air bag deployment, read and
carefully follow all SERVICE PRECAUTIONS and DISABLING &
ACTIVATING AIR BAG SYSTEM procedures in AIR BAG SYSTEM SAFETY
article.
BLOWER MOTOR RELAYS
1) Blower motor relay is located in Power Distribution Center
(PDC). On Ram Van/Wagon, high speed blower motor relay is located in
engine compartment (on side of heater assembly). On all models,
disconnect negative battery cable. Remove blower motor relay. Using an
ohmmeter, check for continuity between terminals No. 87A and 30 of
relay. See Fig. 1. If continuity does not exist, replace relay. If
continuity exists, go to next step.
2) 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.
3) 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.
4) Using jumper wires, connect battery voltage to terminal
No. 86 and ground terminal No. 85. See Fig. 1. 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 blower motor relay. If continuity is as specified,
relay is okay.

Fig. 1: Identifying Blower Motor Relay Terminals
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 blower motor resistor terminals. If continuity exists
between all terminals, go to next step. If continuity does not exist
between all terminals, replace faulty blower motor resistor.
2) Check for open or short in circuits between blower motor
resistor and heater control panel. Also check for open or short in
wire between blower motor resistor and blower motor.
BLOWER MOTOR SWITCH
Dakota, Durango & Ram Pickup
1) Using a voltmeter, check for battery voltage at underhood
power distribution center fuse No. 5 (40-amp) on Dakota and Durango;
fuse No. 12 (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 heater control
panel. See HEATER CONTROL PANEL R & I . Disconnect heater control panel
harness connector. Using an ohmmeter, check for continuity between
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 wire or
Black/Orange wire between 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 heater mode control knob to any position except OFF.

Using an ohmmeter, check for continuity between heater control panel
connector terminal No. 7 and terminals No. 3, 4, 5 and 6 while
rotating blower motor switch. See Fig. 2.
5) If continuity does not exist at any terminal, replace
faulty heater control panel. If continuity exists as specified, check
for open in circuits between heater control panel and blower motor
resistor. Also check for an open in circuit between heater control
panel and blower motor.
Fig. 2: Identifying Blower Motor Switch Connector Terminals (Dakota,
Durango & Ram Pickup)
Courtesy of Chrysler Corp.
Ram Van/Wagon
1) Disconnect negative battery cable. Remove heater control
panel. See HEATER CONTROL PANEL R & I . Disconnect heater control panel
harness connector. Using an ohmmeter, check for continuity between
heater control panel C3 harness connector terminal "C" (Black wire)
and ground. See Fig. 4. Go to next step.
2) If continuity exists, go to next step. If continuity does
not exist, repair open in Black wire between heater control panel and
ground connector located at lower right of steering column.
3) Place heater mode control knob to any position except OFF.
Using an ohmmeter, check for continuity between heater control panel
C3 connector terminals "B" (Violet wire) and "C" (Black wire). If
continuity exists, go to next step. If continuity does not exist,
replace faulty heater control panel.
4) Using an ohmmeter, check for continuity between heater
control panel C3 connector terminal "B" (Violet wire) and C1 connector\
terminal "E" (Violet wire). See Fig. 3. If continuity exists, go to
next step. If continuity does not exist, repair open in Violet wire
between heater control panel C3 and C1 connectors.
5) Using an ohmmeter, check for continuity between heater
control panel C1 connector terminal "E" and terminals "B", "C" and "D"
while rotating blower motor switch. See Fig. 3.
6) If continuity does not exist at any terminal, replace
faulty heater control panel. If continuity exists as specified, check

for open in circuits between heater control panel and blower motor
resistor. Also check for an open in circuit between heater control
panel connector and blower motor relay.
Fig. 3: Identifying Heater Control Panel C1 Connector Terminals
Courtesy of Chrysler Corp.
Fig. 4: Identifying Heater Control Panel C3 Connector Terminals
Courtesy of Chrysler Corp.
HEATER CONTROL PANEL

1) Connect a vacuum gauge in line with Black heater vacuum
supply hose (located at tee near power brake booster, in engine
compartment). Position gauge so it can be viewed from passenger
compartment.
2) Start engine. While observing vacuum gauge, rotate mode
control knob to each mode position (one position at a time). Pause
after each selection. Vacuum gauge should drop then return to 8 in. Hg
shortly after each selection is made. If vacuum gauge reading is as
specified, go to next step. If gauge reading is not as specified,
check for vacuum leak in vacuum lines or heater control panel.
3) Move temperature control knob quickly to full hot and full
cold positions. A distinct sound of blend-air door hitting its stops
should be heard. No spring-back of knob should exist.
4) If temperature control knob operates as specified,
temperature control system is okay. If temperature control knob does
not operate as specified, check condition, routing, installation and
adjustment of temperature control cable. See
TEMPERATURE CONTROL CABLE ADJUSTMENT.
HEATER OUTPUT
1) Start engine. Allow engine to reach normal operating
temperature. With engine at idle, set controls to maximum heat, floor
and high blower positions. Using a thermometer, check air temperature
coming from floor vents. See HEATER OUTPUT TEMPERATURE table.
2) If floor outlet air temperature is lower than specified,
check cooling system and electric cooling fan. See ELECTRIC COOLING
FAN article.
3) Check that both return and supply heater hoses are hot. If
coolant return hose is much cooler than supply hose, repair coolant
obstruction in heater system. Check for air flow obstruction in heater
system. Check blend air door for proper operation.
HEATER OUTPUT TEMPERATURE









\









\









\









\









\









\









\







Ambient Temp. F (C) Outlet Vent Temp. F (C)
Except Durango
60 (15.6) ............................................. 144 (62.2\
)
70 (21.1) ............................................. 147 (63.8\
)
80 (26.6) ............................................. 150 (65.5\
)
90 (32.2) ............................................. 153 (67.2\
)
Durango
60 (15.6) ............................................. 126 (52.2\
)
70 (21.1) ............................................. 133 (56.1\
)
80 (26.6) ............................................. 139 (59.4\
)
90 (32.2) ............................................. 144 (62.2\
)









\









\









\









\









\









\









\







REMOVAL & INSTALLATION
* PLEASE READ THIS FIRST *
WARNING: To avoid injury from accidental air bag deployment, read and
carefully follow all SERVICE PRECAUTIONS and DISABLING &
ACTIVATING AIR BAG SYSTEM procedures in AIR BAG SYSTEM SAFETY
article.
BLEND AIR DOOR MOTOR
Removal & Installation (Ram Pickup)
Remove heater assembly. See HEATER ASSEMBLY. Remove blend air

door servo motor electrical connector and mounting bolts. Remove blend
air door servo motor. Ensure blend air door operates properly without
restriction or binding. To install, reverse removal procedure.
Removal & Installation (Ram Van/Wagon)
Disconnect negative battery cable. Remove glove box.
Disconnect wire harness connector from blend air door motor.
Disconnect blend air door motor lever and remove link from retainer.
Remove 3 mounting bolts and remove blend air door motor.
BLOWER MOTOR
Removal (Dakota & Durango)
1) Disconnect negative battery cable. Remove and disassemble
heater assembly. See HEATER ASSEMBLY. Disconnect blower motor lead at
bottom of housing. Remove 6 bolts and blower motor housing cover.
2) Remove blower motor and fan assembly. Place reference
marks on blower motor and fan for installation reference. Remove
blower fan retainer clip. Pull blower motor fan off blower motor
shaft.
Installation
Align reference marks made during removal. Press blower fan
hub onto blower motor shaft. Ensure retainer clip ears are indexed
over flats of blower motor shaft and fan hub. To complete
installation, reverse removal procedure.
Removal (Ram Pickup)
1) Blower motor is located under glove box and can be removed
from passenger compartment. See Fig. 5. Disconnect negative battery
cable. Disconnect blower motor cooling tube. Remove blower motor
electrical connector from retainer. Disconnect electrical connector.
2) Remove blower motor and fan assembly mounting bolts.
Remove blower motor and fan assembly. Place reference marks on blower
motor and fan for installation reference. Remove blower motor fan
retainer clip. Pull blower motor fan off blower motor shaft.
Installation
Align reference marks made during removal. Press blower fan
hub onto blower motor shaft. Ensure retainer clip ears are indexed
over flats of blower motor shaft and fan hub. Ensure blower motor seal
is installed on housing. To complete installation, reverse removal
procedure.
Removal (Ram Van/Wagon)
1) Disconnect negative battery cable. Remove top half of
radiator shroud. At right side of engine compartment, disconnect
blower motor wiring connector and motor cooling tube. Remove nuts and
washers from blower motor backing plate to heater housing studs. See
Fig. 6 .
2) Remove blower motor assembly. Place reference marks on
blower motor and fan for installation reference. Remove blower motor
fan retainer clip. Pull blower motor fan off blower motor shaft.
Inspect backing plate seal for breaks and adhesion.
Installation
Align reference marks made during removal. Press blower fan
hub onto blower motor shaft. Ensure retainer clip ears are indexed
over flats of blower motor shaft and fan hub. Apply a small bead of
rubber sealant to blower motor side of rubber seal. To complete
installation, reverse removal procedure.

Fig. 5: Identifying Heater Assembly Components (Ram Pickup)
Courtesy of Chrysler Corp.