1993 DODGE TRUCK Service Repair Manual

24
- 28
HEATING
AND AIR
CONDITIONING
—

J8924-40

Fig.
24
Waive
Plate

(5) Visually inspect the rear valves and discharge
retainer for damage. Discard any component if any
portion is damaged.
If valve plate and/or cylinder head are to be reused,
carefully remove gasket materials using the gasket scraper. Do not damage cylinder block or valve plate
surfaces. . . . _ #

E8924-207

Fig.
25 Cylinder Head
Bolt
Torque
Sequence
INSTALLATION

When installing the cylinder head valve plate, use
the new gaskets in the parts kit. (1) Coat new valve plate gasket with clean refrig­
erant oil. (2) Install valve plate gasket by aligning valve
plate gasket to locating pin holes and oil orifice in cylinder block. (For easy reference, the gaskets have a notch at the bottom outside edge). (3) Install valve plate by aligning valve plate lo­
cating pins to the pin holes in the block and position
valve plate. (4) Install cylinder head and tighten bolts in order
to 32 N*m (24 ft. lbs.) torque (Fig. 25).
(3) Visually inspect all parts for damage.
(4) Separate the valve plate from the cylinder
block (Fig. 24).

HEATING
AND
AIR
CONDITIONING
24 - 29
CLIMATE CONTROL
SYSTEM

INDEX

page

Air Conditioner Distribution
and
Spot Cooler
Ducts-Center
. . 38

Air Conditioner Distribution
and
Spot Cooler
Ducts-Left Bi-Level
38

Air Conditioner Distribution
and
Spot Cooler

Ducts-Right
Bi-Level
38

Air
Outlet
Assemblies Right
Side
.............
38

Control Test
......
30
Defroster Duct
34

Electrical Controls
and
Circuits
30
Electronic Temperature Cycling Switch
37

Evaporator Control Unit
. . 34

GENERAL
INFORMATION
This
air
conditioner
is
designed specifically
for
con­
ventional
cab
trucks with
the
heater-evaporator
package designed
to fit
under
the
instrument panel.
The system
is
manually controlled
by the
operator. Controls have been kept simple
for
ease
of
service and operation. In
the
blend
air
reheat
air
conditioning unit,
all

the
air
entering
the
system passes through
the
evap­ orator.
A
selected portion passes through
the
heater
core depending
on the
position
of the
blend
air
door.
The system controls
are
located
in the
center
of the
instrument panel within easy reach
of the
driver.
The combination electrical
and
vacuum switch con­
trols
the
compressor clutch, mode
of
operation
and

blower. Modes
are Off, Max. A/C, A/C,
Vent, Heat and Defrost.
A
4-speed blower motor switch controls
the amount
of air
flow.
The
evaporator-heater pack­ age includes:
•
The
blower motor. • Intake duct with outside
air
recirculating door.
• Evaporator coil
• Heater core.
• Defroster discharge doors.
• Blower motor speed resistors.
• Vacuum harness.
• Vacuum actuators.
•
A/C air
outlets
to the
distribution ducts. Defrost, Heat,
A/C and
Vent modes automatically
supply
100%
outside
air.
The
air
distribution ducts supply
air
from
the
unit
to
4
panel mounted, fully directional, outlets.
The
faceplate
has 2
outlets
and 2 are
snapped into
the

panel
on the
right side. Satisfactory performance
of the air
conditioning
and heating system
is
dependent upon correct opera­
tion
and
adjustment
of all
operating controls.
The in­
spections, tests
and
adjustments should
be
used
to

locate
the
cause
of a
malfunction.
The
tests
in
this
page

Evaporator Heater Assembly
36

Expansion
(H)
Valve
37

Faceplate
32

General Information
. 29

Heater Assembly
. 33

Heater Control
32

Louver
Assemblies
39

Operation
of All
Controls
29
Resistor
Block
33

Temperature
and
Mode Control Cables
. 32
Vacuum
Actuators
36
Vacuum
Controls
and
Circuits
30

manual have been arranged
in a
logical sequence
that
has
proved
to be the
surest
and
shortest route
to
accurate diagnosis.
It is
recommended that they
be

followed
and
performed
in the
order they
are
pre­ sented.

OPERATION
OF ALL
CONTROLS
Operation must
be
tested
as
described
in the
fol­
lowing sequence: (1) Inspect, test,
and
adjust compressor drive belt.
(2) Start engine
and
adjust engine speed
to 1,300

RPM.
Use a
reliable tachometer. (3) Move temperature control lever
to
Cool position
and mode lever
to A/C
position. (4)
The
inlet
air
door should
be
open
to
outside
air.

Open vehicle windows. (5) Test
the
blower operation
at all 4
speed posi­

tions.
If the
blower does
not
operate correctly refer
to

Electrical Controls
and
Circuit. Leave
the
blower switch
in the
HIGH position.
(6)
The
compressor should
be
running
and the air

conditioning system
in
operation. In addition
to the six
position push button selector,
the
A/C
Heater control consists
of:
TEMPERATURE LEVER-Controls
the
tempera-.
ture
of the
discharge
air in all
modes except
MAX

A/C
and Off
when
the
vacuum operated water valve is closed. Moving
the
lever
to the
left provides cooler
air
and
moving
it to the
right provides warmer
air.
BLOWER SWITCH-The system blower
can be op­

erated
at 4
speeds.
•
LOW at the
bottom. • MEDIUM
1 at the
lower center.
• MEDIUM
2 at the
upper center.
• HIGH
at the top
switch position. The blower will
be on and
operating
at the
speed
selected,
in all
push button positions except
Off.
AIR DIRECTIONAL VANES-Air
is
delivered
through
4
panel outlets.
The 4
outlets
are
adjustable

24 - 30
HEATING
AND AIR
CONDITIONING

•
up,
down or to either side and can be shut off by
pushing the vanes up. Floor air is delivered through
the lower outlets.

VACUUM CONTROLS
AND
CIRCUITS
For an explanation of the vacuum and electrical
logic that controls the operation of the unit (Fig. 1
and Control Chart). MODES—The vacuum and electrical logic is deter­
mined by the push button switch. The vacuum por­
tion of the switch controls the water valve and
positions all doors in the unit except the blend air
door. The electrical portion of the switch controls the compressor and blower operation. The following is a
breakdown of the vacuum and electrical logic for each mode. Refer to Control Chart in this section.
OFF Vacuum application is as indicated in Fig. 1. The
inlet air door is closed to outside, open to recirculat­
ing air. The mode door is in the A/C position. The
Heat/Defrost door is in the Heat position. The heater core coolant flow is
shut-off.

No air flows through the unit and the compressor
is idle because the blower and compressor clutch cir­
cuits are open.
MAX A/C All of the doors are in the same position as they
are in Off. The Max. A/C mode merely closes the
electrical circuits to the blower motor and the com­
pressor clutch. This mode is recommended for initial cool down, extreme outside humidity or high ambient
temperature.

A/C
This mode is recommended for use after the vehicle
has been cooled to the desired temperature. The vac­
uum application at the outside-recirculating air door actuator is transferred to the rod side. This moves
the door away from the outside-air inlet and closes
the recirculating inlet. The water valve is open. All
other vacuum applications and door positions are the
same for the Max. A/C position. The blower motor and compressor are on.
VENT The vacuum circuit remains the same as in the
A/C position but the compressor clutch electrical cir­
cuit is opened, preventing the compressor from oper­ ating. The blower motor is used to force outside air
into the passenger compartment through the A/C
outlets in the instrument panel.

HEAT
In the Heat mode the outside air door is open same
as A/C mode. Vacuum is applied to the top side of the air condi­
tioning door actuator. This will close off the passage
to the air conditioning distribution duct and open the
passage to the heater/defroster duct. Since the heat­ er-defroster door is in the heat position, the full flow
of heated air goes through the heater outlets. A
small amount of heated air will bleed through the
defroster outlets. The water valve is open, the blower
switch is activated and the compressor is off.
DEFROST When the defrost mode is selected all conditions
are the same as for heater operation, except that no
vacuum is applied to the defrost door actuator. The defrost door is spring loaded to the defrost position.
The door opens the defroster outlets and partially closes off the heater outlets. The heater outlets are
left open far enough to direct about 30 percent of the
air to the floor. The other 70% is defrost air directed
to the windshield area. The compressor clutch will be engaged.

ELECTRICAL CONTROLS AND CIRCUITS
The electrical feed for the air conditioning circuit is
from 2 fuses in the fuse block. A 20 ampere fuse pro­
tects the compressor clutch circuit, and a 30 ampere fuse protects the blower motor control circuit.

CONTROL TEST
Test operation of controls in the following manner.
(1) Inspect compressor drive belt. Adjust, if neces­
sary. (2) Start engine. (3) Move temperature lever to extreme left (cool)
position. (4) Push A/C button.

(5)
Refer to Control Chart. Check position of doors,
operation of compressor clutch, blower motor and wa­
ter valve. The water valve is open when there is no
vacuum to valve. (6) Check blower switch by moving it to all 4 posi­
tions and noting air flow change. In case of malfunc­
tion refer to Electrical Control Circuit. (7) Check operation of blend air door by moving
temperature lever from full warm toward cool posi­
tion. Discharge air temperature should change with lever movement if the engine coolant is warm. (8) Repeat steps 5 and 6 in each push-button posi­
tion. If actuation of the doors is slow or incomplete,
check for mechanical misalignment, binding or vac­ uum leaks. The air conditioning door has a seven
second vacuum delay in mode switching from Off,
Max A/C, A/C, or Vent to Heat or Defrost. Check
temperature control cable for correct adjustment.

•
HEATING AND AIR CONDITIONING 24 - 31
SOLID
LINE
INDICATES ENGINE
VACUUM
„
VIOLET

CHECK
VALVE f
SOLID
LINE INDICATES

ENGINE
VACUUM
VIOLET

YELLOW
I ACTUATOR ^OUTSIDE
AIR
OFF, MAX A/C

A/C,
VENT

SOLID
LINE
INDICATES
ENGINE
VACUUM VIOLET
RED
/ I

CHECK
VALVE I • DEFROSTER-*-*-
H5WN

RESTRICTOR
DARK

GREEN
AIR/COND.

t
ACTUATOR
I
HEATING
WATER VALVE
ACTUATOR ^
| •

ON
-*-^OFF
YELLOW
HEAT
ACTUATOR
LIGHT
GREEN

RECIRCULATING

GRAY ACTUATOR
OUTSIDE
AIR
SOLID
LINE INDICATES

ENGINE
VACUUM VIOLET
ACTUATOR HEAT
* PUSH BUTTON CONTROL
VACUUM SWITCH
** RESTRICTOR IS PART OF VACUUM CONNECTOR AND NOT VISIBLE ACTUATOR
OUTSIDE
RN1001

Fig. 1
Vacuum
Circuits
(Air
Conditioning
and
Heating)

24 - 32
HEATING
AND AIR
CONDITIONING

CONTROL CHART

Control
Position Off
Max.
A/C

A/C
Vont

Hoot
Defrost
Inlet Air Door (Open To)
Inside Inside

Outside Outside
Outside
Outside

Mode
Door (Open To)
A/C A/C A/C A/C
Heat
Heat
Heat Defrost (Open To) Heat
Heat Heat Heat Heat

Defrost

Compressor
Clutch Off
On On
Off Off
On

Blower
Motor Off
On On On
On On

Water Valve Off Off
On On On
On
FACEPLATE

REMOVAL
(1) Remove map lamp.
(2) Remove screws which attach faceplate to base
panel. Make sure the screw below the Heater-A/C
control is removed (Fig. 2).

MOUNTING
SCREWS

LOCATIONS

RB458

Fig.
2
Mounting
Screw
Location
(3) Pull column shift lever in position 1.
(4) Remove faceplate by pulling the top edge rear­
ward to clear the brow, disengage attaching clips around the bottom of the faceplate, and complete re­
moval of faceplate.

(5)
Disconnect wires to 4 WD indicator, if
equipped.

INSTALLATION
(1) Engage attaching clips around bottom of face­
plate.
(2) Connect 4 WD drive indicator wiring, if
equipped.
(3) Roll faceplate into position and install mount­
ing screws (Fig. 2). (4) Install map lamp.

HEATER
CONTROL
REMOVAL
(1) Remove faceplate.
(2) Remove attaching screws (Fig. 3). (3) Pull control outward.
TAB FLAG
FLAG
RETAINER
J9124-118

MOUNTING
SCREW(2)

HEATER
CONTROL
UNIT
RB459

Fig.
3 Heater Control (4) Disconnect illumination light and switch wir­
ing.
(5) Remove cables.
(6) Remove control unit.

INSTALLATION
(1) Install cables.
(2) Connect illumination light and switch wiring.
(3) Install unit in instrument panel and secure
with mounting screws.
(4) Move the levers to the extreme right to adjust
the clips.
(5) Install faceplate.

TEMPERATURE
AND MODE CONTROL
CABLES
REMOVAL
(1) Remove faceplate.
(2) Open glove box past stops.
(3) Remove control unit from instrument panel.
(4) Remove cables from control lever pins and re­
move flags from retainers (Figs. 4 and 5).
DEPRESS
TAB

FOR
REMOVAL FLAG
RED-TEMPERATURE
DOOR
YELLOW-MODE DOOR
CONTROL
CABLE
ASSEMBLY

PR413C

Fig.
4 Flag Tab
Depressed
for
Removal

•

HEATING
AND AIR
CONDITIONING
24 - 33

Fig.
5 Heater Control
(5)
Detach cables from unit by removing self adjust
clips from crank arms and removing flags from re­
tainers (Fig. 6).

TAB

HOUSING
CRANK
RB461
Fig.
6
Cables
from Unit
(6) Remove cable assemblies through glove box
opening. (7) Place a 7 mm (1/4 inch) I.D. tube over clip and
pry self-adjust clip off core wire if required (Fig. 7).

Fig.
7 Self-Adjusting Clip
INSTALLATION (1) Position self-adjust clip on cable core wire 50
mm (2 inches) from the small loop at heater assem­
bly flag end. With a 7 mm (1/4 inch) I.D. tube, snap self-adjust clip on core wire.
(2) Install cable assemblies through glove box
opening. (3) Attach self-adjust clips to crank arms and re­
place flags in receivers on heater assembly. (4) Install flanges in retainers and attach cables to
control levers on control unit.
(5) Install control unit into instrument panel.
(6) Install faceplate. (7) Move levers to extreme right to adjust clips.

RESISTOR
BLOCK

REMOVAL (1) Remove connector from resistor block.
(2) Remove mounting screws. (3) Remove resistor block from plenum.
INSTALLATION (1) Place resistor block on plenum.
(2) Install mounting screws.
(3) Connect wiring connector.

HEATER
ASSEMBLY

REMOVAL (1) Disconnect the negative cable from the battery.
(2) Remove water hoses on engine side and plug
hoses and inlets on package (Fig. 8).

WIRE
RB464

Fig.
8
Water
Hose
Connections

(3) Remove right cowl side trim panel, if equipped.
(4) Remove glove box by removing mounting
screws at base and swinging out from the bottom to
avoid catch and stops.
(5) Remove structural brace through glove box
opening. (6) Remove right half of instrument panel lower
reinforcement (8 screws). Be sure to disconnect the ground strap. (7) Disconnect control cables. (8) Disconnect blower motor wires on engine side.
(9) Remove screw that retains package to cowl side
sheet metal.

24
- 34
HEATING
AND
AIR
CONDITIONING

• (10) Remove unit retaining nuts
on
engine side
(6

nuts).
(11) Remove unit.
(12) Remove screws
and
mode door crank
to
sepa­
rate cover from housing. (13) Carefully slide heater core
out.

(14) Peel dash panel seal below cover. Remove
re­

taining screws
and
remove cover from blower motor assembly.
(15) Separate
fan
from motor, motor from housing
and inspect
all
parts.
INSTALLATION (1) Assemble heater assembly using necessary
new

parts.

(2) Position heater assembly
to
dash
and
install
re­

taining nuts
on
engine side.
(3) Install cowl side retaining screws.
(4) Connect blower motor.
(5) Connect control cables.
(6) Install right, lower instrument panel reinforce­
ment.
(7) Install structural brace through glove
box
open­
ing.
(8) Install glove
box.

(9) Install right cowl side trim panel,
if
equipped. (10) Unplug inlets
and
water hoses
and
connect
hoses
to
inlets
on
package
(Fig. 8).

(11) Connect
the
negative cable
to the
battery.

DEFROSTER
DUCT
REMOVAL
(1) Disconnect
the
negative cable from
the
battery.
(2) Open glove
box
past stops.
(3)
If
equipped, remove right upper
air
duct
by re­

moving mounting screw
and
pulling duct
out
through
glove
box
openings
(Fig. 9).

(4) Remove instrument panel center brace.
(5) Remove right kick
pad.

(6) Remove right instrument panel pivot bolt.
(7) Remove instrument panel cluster.
(8) Disconnect shift lever cable,
if
equipped.
(9) Lower steering column.
(10) Remove steering column studs. (11) Remove radio,
if
equipped.
(12) Remove mounting screws
and
remove scoop
connecting heater unit
to
center distribution duct,
if

equipped.
(13) Remove mounting screws
and
remove center
distribution duct
by
pulling bottom
of
instrument
panel
out and
dropping duct
out (Fig. 9).

(14) Remove heater control.
(15) Remove mounting screws
and the
cover that
retains instrument panel wiring.
Let
wiring hang

free.
(16) Remove mounting screw
and
slide left
air
duct
out through instrument cluster opening,
if
equipped
(Fig.
9).
(17) Remove screws attaching defroster duct
to

dash panel
(Fig. 9).
(18) Reach
in
through instrument panel opening
and disengage snaps
to
separate defroster duct into
2

pieces.
(19) Remove defroster duct halves through instru­
ment cluster opening.
INSTALLATION (1) Install defroster duct halves through instru­
ment cluster opening. (2) Reach
in
through instrument panel opening
and engage snaps
to
connect defroster duct halves.
(3) Install screws attaching defroster duct
to
dash
panel
(Fig. 9).
(4) Slide left
air
duct
out
through instrument clus­
ter opening,
if
equipped
(Fig. 9).
Install mounting screw.
(5) Position
the
cover that retains instrument
panel wiring. Install mounting screws.
(6) Install
the
heater control.
(7) Position
the
center distribution duct
in
bottom
of instrument panel
out, if
equipped
(Fig. 9).
Install
mounting screws. (8) Position
the
scoop connecting heater unit
to

center distribution duct,
if
equipped. Install mount­ ing screws.
(9) Install
the
radio,
if
equipped.
(10) Install steering column studs.
(11) Position
the
steering column
in
place. (12) Connect shift lever cable,
if
equipped.
(13) Install instrument panel cluster.
(14) Install right instrument panel pivot bolt.
(15) Install right kick
pad.
(16) Install instrument panel center brace.
(17) Position
the
right upper
air
duct
in
through
glove
box
openings,
if
equipped
(Fig. 9).
Install
mounting screw.
(18) Close glove
box.
(19) Connect
the
negative cable
to the
battery.

EVAPORATOR CONTROL UNIT

REMOVAL (1) Remove faceplate.
(2) Remove attaching screws.
(3) Pull control unit
out,
away from instrument
panel. (4) Disconnect blower control switch wiring con­
nector. (5) Disconnect
3
wiring connectors
to
evaporator
control unit. (6) Disconnect illumination light.
(7) Disconnect vacuum harness.
(8) Disconnect temperature control cable.

•
^ ^ ^ ^ ^
^ HEATING
AND AIR CONDITIONING 24 - 35

CENTER DISTRIBUTION DUCT RIGHT SPOT
COOLER DUCT

LEFT
SPOT COOLER DUCT MOUNTING

SCREW

AIR

OUTLET
ASSEMBLIES

HEAT/DEFROST
DOOR ACTUATOR DEFROSTER
DUCT
MOUNTING
SCREW

TEMPERATURE CONTROL
CABLE
(RED
FLAG) MOUNTING.

HARNESS

TAB VACUUM

HARNESS
MOUNTING
NUT BLOWER
MOTOR

RECEIVER
TEMPERATURE
CONTROL LEVER HEATER-A/C
CONTROL ASSEMBLY MOUNTING
NUT
BLOWER MOTOR
FEED WIRES VACUUM
LINES

i
DRAIN TUBE RB4#B

Fig.
9
Heater and Evaporator Assembly