1993 DODGE TRUCK low oil pressure

•

HEATING
AND
AIR
CONDITIONING
24 - 19
Connect
the
compound gauge hose
to the
compres­
sor suction service valve gauge port (low-side).
Connect
the
high pressure gauge hose
to the
dis­
charge service valve gauge port (high-side). Purge
air
from
the
high side test hose
by
opening
the high side hand valve
on the
manifold
for 3 to 5
seconds.
The
center connection
on the
manifold must
be open.
Purge
air
from
the low
side test hose
by
opening
the
low
side hand valve
on the
manifold
for 3 to 5
seconds.
The
center connection
on the
manifold must
be open.
The
air
conditioning system
may be
operated with
the gauge manifold assembly connected
in
this man­
ner.
The
gauges will indicate respective operative
pressures.

DISCHARGING
THE SYSTEM
Since
the air
conditioning refrigerant system
is

pressurized,
it
will
be
necessary
to
completely dis­ charge
the
system before replacing
any
refrigerant
components.
The
procedure
is as
follows: (1) Install gauge
set as
described under manifold
gauge
set
installation. Make sure
the
gauge
set

valves
are
closed before attaching
the
hoses
to the re­

frigerant system. (2) Install
a
long hose
to the
manifold gauge
set

connector.
Run
this hose
to the oil
collector
can
near
the shop exhaust system. A good
oil
collector
can may be
made from
a
large
empty coffee
can
with
a
plastic
top.
Slit
the
plastic
top
in the
form
of a Y to
make
an
entrance
for the
refrigerant hose
and
exit
for the gas.
(3) Open
the
compressor discharge
and
suction line
pressure valves
and
discharge
the
refrigerant into
the
oil
collector
can.
Watch
to
make sure
the
hose does
not
blow
out of the
collector
can.
(4) When
the
system
has
been completely dis­
charged, measure
the
amount
of oil
collected
in the

can.
The
amount
of oil
measured should
be
added
to

the refrigerant system before
it is
charged. Discard
the used
oil. Add new oil.

EVACUATING
THE SYSTEM
Whenever
the
system
has
been opened
to the
atmo­
sphere,
it is
absolutely essential that
the
system
be

evacuated
to
remove
all the air and
moisture.
Air in

the refrigerant system causes high compressor dis­ charge pressures,
a
loss
in
system performance,
and

oxidation
of the
compressor
oil
into
gum and
varnish.
Moisture
in the
refrigerant system
can
cause
the ex­

pansion valve
to
malfunction. Under certain condi­
tions
it can
react with
the
refrigerant
to
form destructive acids.
It is
necessary
to
adhere
to the
fol­
lowing procedure
to
keep
air and
moisture
out of the
system. (1) Connect
the
manifold gauge
set to the
compres­
sor
and
long test hose from manifold gauge
set
center
connection
to
Vacuum Pump Tool C-4289. (2) Open both manifold gauge
set
valves.
(3) Start
the
vacuum pump
and
operate until
the

evaporator suction gauge registers
at
least
-88
kPag (26 inches
of
vacuum).
If at
least
-88
kPag
(26
inches
of vacuum) cannot
be
obtained, either
the
system
has

a leak
or the
vacuum pump
is
defective. Check
the

vacuum pump.
If the
pump proves
to be
functioning
properly,
the
system
has a
leak. Charge
the
system
with
1
pound
of
refrigerant. Locate
and
repair
all
leaks.
Discharge
the
refrigerant
and
evacuate
the
system.
(4) Continue
to
operate
the
pump
for at
least
5

minutes.
(5) Close manifold valves. Turn
off the
vacuum
pump
and
observe evaporator suction gauge
for 2
minutes.
The
vacuum level should remain constant.
If
the
vacuum level falls
off, the
system
has a
leak. Charge
the
system with
450 g (1
pound)
of
refriger­
ant. Locate
and
repair
all
leaks. Discharge
the
sys­
tem
and
repeat evacuation procedure.

CHARGING
THE
SYSTEM
The refrigerant system must have been evacuated
using
the
previous procedure before charging. Charge
using only
R-12
refrigerant.
R-12 is
available
in
bulk
tanks
or 437 g (14 oz.)
cans. The special refrigerant dispensing manifold per­
mits charging
3
cans
of
refrigerant
at a
time. When
using disposable cans
of
this type, carefully follow
the
can
manufacturers instructions.

WARNING: NEVER USE THESE CANS
TO
CHARGE
INTO
THE
HIGH
PRESSURE SIDE
OF
THE
SYSTEM

(COMPRESSOR
DISCHARGE PORT)
OR
INTO
A
SYSTEM
THAT
IS AT
HIGH
TEMPERATURE.
THE
HIGH
SYSTEM PRESSURES COULD
BE
TRANS­

FERRED
INTO
THE
CHARGING
CAN
CAUSING
IT

TO EXPLODE.

Keep
the
refrigerant manifold valves capped when
not
in use.
Keep
a
supply
of
extra refrigerant-can-to
refrigerant-manifold gaskets
on
hand
so the
gaskets can
be
replaced periodically. This will insure
a
good
seal without excessive tightening
of the can or the

manifold nuts.
(1) Attach center hose from manifold gauge
set to

refrigerant dispensing manifold. Turn refrigerant manifold valves completely counterclockwise
so
they are fully open. Remove protective caps from refriger­
ant manifold.
(2) Screw refrigerant cans into manifold.
Be
sure
manifold-to-can gasket
is in
place
and in
good condi­
tion. Tighten
can and
manifold nuts
to 9.5 N»m (7 ft.
lbs.) torque.

24
- 20
HEATING
AND AIR
CONDITIONING

• (3) Turn
3
refrigerant manifold valves completely
clockwise
to
puncture
the
cans
and
close
the
mani­
fold valves.
(4) Purge
the air
from
the
charging line
by
loosen­
ing
the
charging hose
at the
manifold gauge
set and

turn
one of the
refrigerant valves counterclockwise. When
the
refrigerant
gas
starts escaping from
the

loose connection, tighten
the
hose.
(5) Fully open
all 3
refrigerant manifold valves
and place
the
cans
of
refrigerant into
a pan
contain­
ing 52°C (125°F) water.
The
water will warm
the

charging
can and aid in the
transfer
of the
charge
into
the
system.
(6) Start
the
engine
and
move
the
controls
to A/C

low blower position.
The electronic temperature cycling switch will pre­
vent
the
clutch from engaging until refrigerant
is
added
to the
system.
If the
clutch does engage,
re­

place
the
switch before proceeding
any
further. (7) Charge through
the
suction side
of the
system
by slowly opening
the
suction manifold valve. Adjust
the valve
as
necessary
so
charging pressure does
not
exceed
345
kPag
(50
psig). Maintain
the
temperature
of
the
water
in the pan by
adding warm water
as

necessary. (8) Adjust
the
engine speed
to a
fast idle
of
approx­
imately
1,300 RPM.
(9) When
all 3
cans
of
refrigerant
are
completely
empty, close
the
manifold gauge
set
valves
and re­

frigerant manifold valves. The maximum refrigerant charge
is 44 oz.

REFRIGERANT
LEAK REPAIR PROCEDURE

LOST CHARGE If
the
system
has
lost
all
charge
due to a
leak: (1) Evacuate
the
system.
(2) Charge
the
system with approximately
1
pound
of refrigerant. (3) Locate
all
leaks.
(4) Repair
all
leaks.
(5) Replace filter-drier bottle.

CAUTION:
Replacement
filter-drier
units
must
be

sealed
while
in
storage.
The
drier
used
in
these

units
absorbs
and
traps
moisture
quickly
upon
ex­

posure
to the
atmosphere.
When
installing
a
drier,

have
all
tools
and
supplies ready
for
quick
reas­

sembly
to
avoid keeping
the
system open
any
longer
than
necessary.

(6) Check system
oil
level. (7) Evacuate
and
charge
the
system.
LOW CHARGE If
the
system
has not
lost
all of its
refrigerant
charge; locate
and
repair
all
leaks.
If it is
necessary
to increase
the
system pressure
to
find
the
leak
(be­
cause
of an
especially
low
charge),
add 230 g (1/2 lb)

of refrigerant.
If
there
has
been
a
significant
oil
loss,
check
the
system
oil
level.
If
leak repair
was
possible
without discharging system
and an oil
level check
was
not
necessary,
use
procedure
for
correcting
low

refrigerant level.

CORRECTING
LOW
REFRIGERANT LEVEL
Since
the
refrigeration system
is
completely sealed,
the refrigerant level will
not be low
unless there
is a
leak
in the
system. Before adding refrigerant where
the
cause
of a low

level
is not
known,
the
system should
be
tested
for

leaks.
Assuming that leaks have been corrected without
discharging
the
system, proceed with partial charge.
Install
and
connect manifold gauge
set.
(1) Close both manifold gauge
set
valves. Open
manifold gauge
set
needle valve.
(2) Connect
the
suction gauge test hose
to the
suc­
tion service port
of the
compressor. Connect
the
dis­ charge gauge test hose
to the
discharge service port. (3) Connect
an end of
long test hose
to the
center
manifold outlet,
and
other
end to
refrigerant dispens­ ing manifold. (4) Close
the 2
dispensing manifold valves
and

open remaining dispensing manifold valve. Remove
protective
cap
from opened valve.

WARNING: NEVER
USE
THESE CANS
TO
CHARGE
INTO
THE
HIGH
PRESSURE SIDE
OF
THE
SYSTEM

(COMPRESSOR
DISCHARGE
PORT)
OR
INTO
A
SYSTEM
THAT
IS AT
HIGH
TEMPERATURE.
THE
HIGH
SYSTEM PRESSURES COULD
BE
TRANS­
FERRED
INTO
THE
CHARGING
CAN
CAUSING
IT

TO EXPLODE.

(5) Screw
a can of R-12 to the
opened manifold
valve.
Be
sure gasket
is in
place
and in
good condi­
tion. Tighten refrigerant
can and
manifold locking nut
to
ensure
a
good seal.
Do not
overtighten.
Tighten
to 9.5 N*m (7 ft. lbs.)
torque,
if
gasket
is in
good condition.
(6) Turn manifold valve (above
the
refrigerant
can)

completely clockwise
to
puncture
the can.
This closes
the valve
and
seals
the
refrigerant
in the can.

CAUTION:
Do not
heat refrigerant
12
above
52°C

(125°F).

(7) Place refrigerant
can in a
large
pan of
water
heated
to
52°C (125°F). Place
pan of
water containing
the refrigerant
can on an
accurate scale
so the
amount
of
refrigerant added
can be
weighed. Open
the refrigerant manifold valve.
(8) Purge
all air
from test hoses.
Air in the
system
will
be
trapped
in the
condenser causing abnormally
high discharge pressures
and
interfering with con­ densing
of the
refrigerant.

•

HEATING
AND AIR
CONDITIONING
24 - 21 (a) Loosen both test hoses at the manifold gauge
set. Tighten the hoses as soon as the air is purged. (b) Loosen charging hose connection at manifold
gauge set. This will purge air from the charging

hose.
Tighten connection as soon as air is purged.
(9) With vehicle windows open and hood up, oper­
ate engine at 1,300 RPM. (10) Place air conditioner control on A/C and place
the fan switch on high. (11) If necessary, block the condenser to maintain
a discharge pressure of 1 550-1 725 kPag (225-250

psig).
System must be charged through the evapora­
tor suction service ports as follows:
(a) Slowly open the suction service gauge valve.
Meter flow of refrigerant by adjusting the suction service gauge valve so the pressure registered at
the suction service gauge does not exceed 345 kPag

COMPRESSOR
J
(50
psig). Keep refrigerant container upright.
(b) Add refrigerant gas until there is no foam visi­
ble at the sight glass. As soon as all foam clears, note the weight registered on the refrigerant scale.
(c) Watch the refrigerant weighing scale and add
437 g (14 oz.) of refrigerant (equivalent to 1 can).
(d) Close the suction gauge valve.

CAUTION:
TOO
much
refrigerant
in the
system
can

cause
abnormally high discharge pressures. Care
must
be
used
so the
exact recommended amount
of
refrigerant
is
added
after
foam clears
in the
sight

glass.

(e) Close dispensing manifold valve. Remove test
hoses and adapters from the service ports of com­
pressor and install protective caps at service ports.

RVICE (SD-709)

INDEX

page

Compressor
21

Compressor
Shaft Seal
.................... 25
The A/C system uses a 7 piston design Sanden SD-
709 compressor. Designated the SD-709, the compres­
sor is mounted on the front right side of the engine
and is driven by a serpentine belt.
System lubrication is provided by 135cc ±15cc (4.6
cu. in. ±0.5 cu. in.) of 500 viscosity refrigerant oil.
The clutch used on the compressor consists of 3 ba­
sic components:
(1) The pulley.
(2) The front plate. (3) The field coil.
The pulley and field coil are attached to the front
head of the compressor with snap rings. The hub is keyed to the compressor shaft and is retained on the
shaft with a self-locking nut. Special service tools are
required to remove and install the clutch plate on
the compressor shaft.

COMPRESSOR
REMOVAL
(1) Disconnect the negative cable from the battery.
(2) Disconnect the clutch lead wire.
(3) Remove the discharge and inlet (suction) ser­
vice valves from the compressor. Plug or tape all the
openings.
(4) Refer to Group 7, Cooling System and remove
the drive belt(s). (5) Remove the bolts and lift the compressor from
the mounting bracket (Fig. 1).
page

Cylinder Head
/
Valve Plate
27
Magnetic
Clutch
22

Fig.
1
Compressor
Mounting

INSTALLATION
If a replacement compressor is being installed,
check the oil level. Add or subtract oil as necessary.
Install the magnetic clutch on the compressor.
(1) Install the compressor on the mounting bracket.
Tighten the bolts to 27 N*m (20 ft. lbs.) torque.
(2) Refer to Group 7, Cooling System and install
the drive belt(s).
(3) Check the belt tension.
@ New drive belt-800-900 N (180-200 lbs-f).
• Used belt-623-712 N (140-160 lbs-f).

•

Fig.
12
Blower
Wheel
(7) Install the 3 arms. Install nut that attaches 3
door arms to doors on the top cover of the unit (Fig.
11).

INSTALLATION
(1) Install the evaporator heater assembly. Plastic
instrument panel may have to be flexed outward.
(2) Install and tighten the screw that retains the
evaporator heater assembly to cowl side sheet metal.
(3) Install the retaining nuts on engine side.
(4) Connect vacuum lines on engine side.
(5) Install blower motor connector on engine side.
(6) Remove wiring connector from resistor block.
(7) Connect vacuum lines from extension on con­
trol unit and attach vacuum lines to defroster duct (Fig. 10).
(8) Connect temperature control cable to unit
through glove box. (9) Install floor air distribution duct.
(10) Install center distribution duct.
(11) Attach radio ground strap. (12) Remove right half of lower reinforcement by
removing screws attaching it to the instrument panel and the screw attaching it to the cowl side trim
panel. (13) Install ash receiver.
(14) Install structural brace through glove box
opening. Install screws and loosen nuts. (15) Install glove box by installing mounting
screws. (16) Install right cowl side trim panel, if so
equipped. (17) Position transfer case and/or gear shift levers.
(18) Remove plugs from heater hoses and unit. In­
stall condensate tube (Fig. 9). (19) Connect refrigerant and heater lines to unit
on engine side.
} (20) Connect the negative cable to the battery. (21) Fill the cooling system (refer to Group 7, Cool­
ing System). (22) Evacuate and charge the system.
(23) Check operation of all controls and perfor­
mance of the A/C system.
HEATING
AND AIR
CONDITIONING
24 - 37

'H"
VALVE

Fig.
13
Expansion
(H)
Valve
Assembly
ELECTRONIC
TEMPERATURE
CYCLING
SWITCH

REMOVAL
(1) Remove the electrical wires to the switch.
(2) Rotate switch counterclockwise to remove from
pressure switch port. (3) Remove and discard old O-ring.

INSTALLATION
(1) Install new O-ring. Refrigerant oil must be ap­
plied to the new O-ring.
(2) Rotate switch clockwise to install on suction
line pressure switch port. Tighten switch to 5.65 N#m (50 in. lbs.) torque.

CAUTION:
Power
tools
should
not be
used
for in­

stallation
of the switch. The
possibility
of stripping
the
switch
threads
occurs
above
5.88 N*m (52 in.
lbs.)
torque.
(3) Connect wires. (4) Verify operation.

EXPANSION
(H)
VALVE

REMOVAL
The system must be completely discharged before
opening any refrigerant lines. (1) Remove the bolt in center of plumbing sealing
plate (Fig. 13).
(2) Carefully pull refrigerant line assembly to­
wards front of vehicle. Take care NOT to scratch valve sealing surfaces with tube pilots.
(3) Remove the Torx Head screws (Fig. 13). Hold
valve, once cap screws are removed valve is com­
pletely disconnected.
(4) Carefully remove valve.

25 - 16
EMISSION
CONTROL
SYSTEMS

•

DOWNSTREAM
dciicc
HOSE
RELIEF
HOLES
J9325-37

Fig.
2 Air Injection
Pump
Operation cessive noise is fault of air injection system, discon­
nect drive belt and operate engine.
CAUTION:
Do not lubricate air injection pump. Wipe
all oil off of pump
housing.
Oil in the pump
will
cause
rapid deterioration and failure.

CAUTION:
Completely cover the air pump before

cleaning
the engine or underhood compartment. Refer to the Component Removal/Installation section
of this group for air pump replacement procedures.

CHECK
VALVE—AIR
INJECTION
TUBE
A check valve (Fig. 1) is located on each of the air
injection downstream tubes. The check valve has a one-way diaphragm which pre­
vents hot exhaust gases from backing up into the hose and pump. The check valve will protect the system if
the air injection pump belt fails, an air hose ruptures or exhaust system pressure becomes abnormally high.

TESTING
CHECK
VALVE
The check valves are not repairable. To determine
condition of valve, remove the rubber air tube from
the inlet side of each check valve. Start the engine. If
exhaust gas is escaping through the inlet side of
valve, it must be replaced.
Refer to the Component Removal/Installation section
of this group for check valve replacement procedures.

AIR
PUMP
DIAGNOSIS

Condition
Possible
Cause
Correction

EXCESSIVE
BELT
NOISE
(a)
Loose
belt
or defective auto,
belt
tensioner. (a) Refer to
Group
7,
Cooling.

(b) Seized pump. (b) Replace pump.

EXCESSIVE
PUMP
NOISE.

CHIRPING
(a) Insufficient break-in.
(a) Recheck for
noise
after
1600 km.

(1,000
miles) of operation.

EXCESSIVE
PUMP
NOISE CHIRPING,
RUMBUNG, OR KNOCKING (a) Leak in
hose.

(a) Locate
source
of leak
using
soap

solution
and correct.
(b)
Loose
hose.
(b)
Reassemble
and replace or tighten

hose
clamp.
(c)
Hose
touching other engine parts. (c) Adjust
hose
position.

(d) Relief valve inoperative. (d) Replace
relief
valve.
(e) Check valve inoperative. (e) Replace check valve.
(f)
Pump
mounting fasteners
loose.
(f) Tighten mounting
screws
as specified.

(g)
Pump
failure.
(g)
Replace pump.
NO AIR SUPPLY (ACCELERATE ENGINE TO 1500 RPM AND OBSERVE AIR
FLOW
FROM

HOSES.
IF THE
FLOW
INCREASES
AS
THE

RPM'S
INCREASE, THE
PUMP
IS
FUNCTION­
ING NORMALLY. IF NOT, CHECK POSSIBLE

CAUSE.
(a)
Loose
drive belt.
(b)
Leaks
in
supply
hose.

(c) Leak at fitting(s). (a) Refer to
Group
7,
Cooling.

(b) Locate leak and repair or replace as required.
(c) Tighten or replace
clamps.

(d) Check valve inoperative. (d) Replace check valve.
J9325-38

•

EMISSION
CONTROL SYSTEMS
25 - 19
EGR
VALVE

REMOVAL

The EGR valve and the electric EGR transducer
(EET) are serviced as one unit.
(1) Disconnect vacuum hose to EGR valve/trans­
ducer assembly. Note position of hoses on EGR valve
and transducer for easier installation.
(2) Remove EGR mounting bolts (Fig. 5).

Fig.
5 EGR
Valve
Mounting
Bolts

(3) Remove EGR valve and gasket. Discard old
gasket. Clean intake manifold mating surface and
check for cracks.

INSTALLATION
(1) Place new EGR gasket on intake manifold. (2) Install EGR valve. Tighten mounting bolts to
23 N*m (200 in. lbs.) torque. (3) Connect vacuum hose to valve/transducer as­
sembly.

EGR
TUBE-GAS POWERED ENGINES

REMOVAL
(1) Remove air filter housing.
(2) Remove the spark plug cable loom and plug ca­
bles from valve cover mounting stud at rear of right
valve cover. Position spark plug cables to top of valve cover.
(3) Disconnect two vacuum hoses at exhaust gas
recirculation (EGR) valve. (4) Remove 2 EGR valve mounting bolts (Fig. 5)
and remove EGR valve. Discard old gasket.
(5) Disconnect electrical connector at engine oil
pressure sending unit.
(6) To prevent damage to oil pressure sending unit,
a special tool, such as number C-4597 must be used
(Fig. 6). Remove sending unit from engine.
(7) Loosen EGR tube mounting nut at intake man­
ifold (Fig. 7).
Fig.
6 Oil
Pressure
Sending
Unit—Removal/Installation

Fig.
7 EGR Tube—Typical
(8) Remove EGR tube mounting bolts at exhaust
manifold (Fig. 7) and remove EGR tube.

INSTALLATION
(1) Clean the EGR tube and exhaust manifold (at
EGR tube mounting point) of any old gasket mate­

rial.
(2)
Install a new gasket to exhaust manifold end of
EGR tube. (3) Install EGR tube to both manifolds. Tighten
mounting nut at intake manifold. Tighten two
mounting bolts at exhaust manifold to 23 N»m (204 in. lbs.) torque.
(4) Coat the threads of the oil pressure sending
unit with thread sealant. Do not allow any of the
thread sealant to get into the sending unit opening
or the opening at the engine. Install sending unit to