1998 DODGE RAM 1500 heating and cooling

CAUTION: Do not apply more than 138 kPa (20 psi)
air pressure to the charge air cooler system, sever
damage to the charge air cooler system may occur.
(3) Connect a regulated air supply to air fitting on
Tool 9022 Adapter. Set air pressure to a Maximum of
138 kPa (20 psi).
(4) Using soapy water check the rubber sleeves,
charge air cooler and intake manifold for leaks.
REMOVAL
WARNING: IF THE ENGINE WAS JUST TURNED
OFF, THE AIR INTAKE SYSTEM TUBES MAY BE
HOT.
(1) Disconnect the battery negative cables.
(2) Discharge the A/C system (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - STAN-
DARD PROCEDURE) and remove the A/C condenser
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING/A/C CONDENSER - REMOVAL) (if A/C
equipped).
(3) Remove the transmission auxiliary cooler
(Refer to 7 - COOLING/TRANSMISSION/TRANS
COOLER - REMOVAL).
(4) Remove the boost tubes from the charge air
cooler (Fig. 24).
(5) Remove the charge air cooler bolts. Pivot the
charge air cooler forward and up to remove.
CLEANING
CAUTION: Do not use caustic cleaners to clean the
charge air cooler. Damage to the charge air cooler
will result.
NOTE: If internal debris cannot be removed from
the cooler, the charge air cooler MUST be replaced.
(1) If the engine experiences a turbocharger failure
or any other situation where oil or debris get into the
charge air cooler, the charge air cooler must be
cleaned internally.
(2) Position the charge air cooler so the inlet and
outlet tubes are vertical.
(3) Flush the cooler internally with solvent in the
direction opposite of normal air flow.
(4) Shake the cooler and lightly tap on the end
tanks with a rubber mallet to dislodge trapped
debris.
(5) Continue flushing until all debris or oil are
removed.
(6) Rinse the cooler with hot soapy water to
remove any remaining solvent.
(7) Rinse thoroughly with clean water and blow
dry with compressed air.
INSPECTION
Visually inspect the charge air cooler for cracks,
holes, or damage. Inspect the tubes, fins, and welds
for tears, breaks, or other damage. Replace the
charge air cooler if damage is found.
Pressure test the charge air cooler, using Charge
Air Cooler Tester Kit #3824556. This kit is available
through CumminstService Products. Instructions
are provided with the kit.
INSTALLATION
(1) Position the charge air cooler. Install the bolts
and tighten to 2 N´m (17 in. lbs.) torque.
(2) Install the air intake system tubes to the
charge air cooler. With the clamps in position, tighten
the clamps to 11 N´m (95 in. lbs.) torque.
(3) Install the transmission auxiliary cooler (if
equipped) (Refer to 7 - COOLING/TRANSMISSION/
TRANS COOLER - INSTALLATION).
(4) Install the A/C condenser (if A/C equipped)
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING/A/C CONDENSER - INSTALLATION).
Recharge A/C system (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - STANDARD PRO-
CEDURE).
(5) Connect the battery negative cables.
(6) Start engine and check for boost system leaks.
Fig. 24 Air Intake System Tubes
1 - BOLT
2 - CHARGE AIR COOLER
3 - CLAMP
4 - BOOST TUBE
DREXHAUST SYSTEM 11 - 17
CHARGE AIR COOLER AND PLUMBING (Continued)

STANDARD PROCEDURE - HYDROFORM
FENDER RAIL REPAIR
CAUTION: This repair procedure assumes damage
to the right or left hydroform fender rail (Fig. 18).
Prior to any repairs, the vehicle must be mounted
on the appropriate frame repair equipment (ªframe
rackº), checked with three dimensional measuring
equipment, and necessary pull corrections made. If
damage exists in the hydroform fender rail, or cab
beyond the area covered by this service procedure
after dimensional corrections are made, the hydro-
form must be replaced in its entirety. Refer to 23 -
BODY/BODY STRUCTURE/WELD LOCATIONS -
SPECIFICATIONS, when replacing the entire hydro-
form.
(1) Before proceding with this repair procedure
review the required service warnings and precau-
tions. (Refer to 13 - FRAME & BUMPERS/FRAME -
WARNING)
(2) Disconnect and isolate the battery negative
cable.
(3) Remove the front wheelhouse splash shield.
(Refer to 23 - BODY/EXTERIOR/FRONT WHEEL-
HOUSE SPLASH SHIELD - REMOVAL)(4) Remove the fender. (Refer to 23 - BODY/EXTE-
RIOR/FRONT FENDER - REMOVAL)
(5) Remove the A/C condenser, if required. (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMB-
ING/A/C CONDENSER - REMOVAL)
(6) Remove the A/C lines, if required. Refer to the
Heating and Air Conditioning section of the manual
for recommended procedures.
(7) Remove the radiator assembly. (Refer to 7 -
COOLING/ENGINE/RADIATOR - REMOVAL)
(8) Remove the air cleaner and support bracket, if
required. (Refer to 9 - ENGINE/AIR INTAKE SYS-
TEM/AIR CLEANER ELEMENT - REMOVAL)
(9) Remove the integrated power module. (Refer to
8 - ELECTRICAL/POWER DISTRIBUTION/INTE-
GRATED POWER MODULE - REMOVAL)
(10) Remove the bolts and position aside the wire
harness and grounds, if required.
(11) Remove the upper radiator crossmember.
(Refer to 23 - BODY/EXTERIOR/UPPER RADIATOR
CROSSMEMBER - REMOVAL)
(12) Remove the headlamp unit. (Refer to 8 -
ELECTRICAL/LAMPS/LIGHTING - EXTERIOR/
HEADLAMP UNIT - REMOVAL)
(13) Remove the front cab mount to the Front End
Sheet Metal bracket (FESM) bolt.
Fig. 18 HYDROFORM FENDER RAILS
1 - HYDROFORM FENDER RAIL
2 - FRONT END SHEET METAL BRACKET
3 - UPPER RADIATOR CROSSMEMBER BOLTS (4)4 - UPPER RADIATOR CROSSMEMBER
5 - LOWER RADIATOR CROSSMEMBER BOLTS (8)
6 - LOWER RADIATOR CROSSMEMBER
DRFRAMES & BUMPERS 13 - 11
FRAME (Continued)

(14) Remove the bolts attaching the lower radiator
crossmember to the hydroform fender rail. (Fig. 18)
CAUTION: Do not use any flame or plasma cutting
equipment to cut the frame in this procedure. The
inaccurate and high temperatures achieved during
flame or plasma cutting will change the metal char-
acteristics and may weaken the frame and/or repair
location.
(15) Using a reciprocating saw or equivalent, cut
the fender rail and shotgun at a straight and square
section of the hydroform and remove.
(16) Smooth and square the cut edges.
(17) Using the damaged structure as a reference
cut the service part at the same location as the first
cut. Smooth and square the cut edges.
NOTE: The repair structure should butt up to the
remaining structure and provide the same overall
vehicle geometry.
(18) Fabricate 51 mm (2.0 in.) long repair inserts
using scrap from the old structure or the replacement
part. It will be necessary to split the inserts on each
of their four sides to fit into the hydroform.
(19) Remove any paint or e-coat from the inserts
and also to the interior and exterior of the hydro-
forms.
(20) Cut plug weld holes as described below.
²On the upper rail, cut one 13 mm (0.5 in.) hole
on each side of the rail, 25 mm (1.0 in.) from the butt
joint of the tubes.
²On the lower rail, cut one 13 mm (0.5 in.) hole
on the top and bottom sides of the rail 25 mm (1.0
in.) from the butt joint of the tube.
²On the lower rail, cut two 13 mm (0.5 in.) holes
on the inner and outer sides of the rail 25 mm (1.0
in.) from the butt joint of the tube.
CAUTION: Shield the surrounding area and compo-
nents from exposure to the welding spatter and
heat.
(21) Install the insert 1º into the replacement part
and tack into place with a weld. (Refer to 13 -
FRAME & BUMPERS/FRAME - SPECIFICATIONS -
WELDING)
(22) Insert the service part into place and using
the appropriate measuring equipment, verify the
front end sheet metal bracket's location in all three
(X,Y, and Z) planes of space. (Fig. 19)
(23) Complete all 360É plug welds.
NOTE: Before the final welding, use three dimen-
sional measuring equipment to ensure the part is in
the correct location. Verify that tap plate extrusion
at the bottom of the vertical post lines up with theisolator and hole in the frame perch mount. Also
ensure the lower radiator closure tube is bolted into
the forward shotgun ends.
(24) Complete welding by making a 360É butt weld
around the fender rails.
(25) Metal finish the exposed welds on the hydro-
forms.
(26) Dress the welded area and apply corrosion
resistant coatings inside and out.
(a) Inside the rail, inject a creeping wax based
rust inhibitor compound to the inside of the hydro-
forms ensuring 100% coverage including the mat-
ing face between the fender rail sections and insert
such that corrosion protection is restored in the
internal cavity.
(b) Apply a durable top coat to the outside of the
repair area.
(27) Install the front cab mount bolt if previously
removed and tighten to 81 N´m (60 ft. lbs.).
(28) Install the lower radiator crossmember bolts
and tighten to 28 N´m (21 ft. lbs.).
(29) Install the headlamp unit. (Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING - EXTERIOR/HEAD-
LAMP UNIT - INSTALLATION)
(30) Install the upper radiator crossmember. (Refer
to 23 - BODY/EXTERIOR/UPPER RADIATOR
CROSSMEMBER - INSTALLATION)
(31) Install the wire harness and ground if previ-
ously removed and install the bolts.
(32) Install the integrated power module, if previ-
ously removed. (Refer to 8 - ELECTRICAL/POWER
DISTRIBUTION/INTEGRATED POWER MODULE -
INSTALLATION)
(33) Install the air cleaner bracket and air cleaner,
if previously removed. (Refer to 9 - ENGINE/AIR
INTAKE SYSTEM/AIR CLEANER ELEMENT -
INSTALLATION)
(34) Install the radiator assembly. (Refer to 7 -
COOLING/ENGINE/RADIATOR - INSTALLATION)
(35) Install the A/C lines, if previously removed.
Refer to the Heating and Air Conditioning section of
the manual for the recommended procedures.
(36) Install the A/C condenser, if previously
removed. (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING/A/C CONDENSER - INSTAL-
LATION)
(37) Install the fender. (Refer to 23 - BODY/EXTE-
RIOR/FRONT FENDER - INSTALLATION)
(38) Install the front wheelhouse splash shield.
(Refer to 23 - BODY/EXTERIOR/FRONT WHEEL-
HOUSE SPLASH SHIELD - INSTALLATION)
(39) Reconnect the battery ground.
13 - 12 FRAMES & BUMPERSDR
FRAME (Continued)

(2) Heavy duty operation with a vehicle not prop-
erly equipped for this type of operation. Trailer tow-
ing or similar high load operation will overheat the
transmission fluid if the vehicle is improperly
equipped. Such vehicles should have an auxiliary
transmission fluid cooler, a heavy duty cooling sys-
tem, and the engine/axle ratio combination needed to
handle heavy loads.
DIAGNOSIS AND TESTING - FLUID
CONTAMINATION
Transmission fluid contamination is generally a
result of:
²adding incorrect fluid
²failure to clean dipstick and fill tube when
checking level
²engine coolant entering the fluid
²internal failure that generates debris
²overheat that generates sludge (fluid break-
down)
²failure to replace contaminated converter after
repair
The use of non-recommended fluids can result in
transmission failure. The usual results are erratic
shifts, slippage, abnormal wear and eventual failure
due to fluid breakdown and sludge formation. Avoid
this condition by using recommended fluids only.
The dipstick cap and fill tube should be wiped
clean before checking fluid level. Dirt, grease and
other foreign material on the cap and tube could fall
into the tube if not removed beforehand. Take the
time to wipe the cap and tube clean before withdraw-
ing the dipstick.
Engine coolant in the transmission fluid is gener-
ally caused by a cooler malfunction. The only remedy
is to replace the radiator as the cooler in the radiator
is not a serviceable part. If coolant has circulated
through the transmission, an overhaul is necessary.
The torque converter should also be replaced when-
ever a failure generates sludge and debris. This is
necessary because normal converter flushing proce-
dures will not remove all contaminants.
STANDARD PROCEDURE
STANDARD PROCEDURE - FLUID LEVEL
CHECK
Low fluid level can cause a variety of conditions
because it allows the pump to take in air along with
the fluid. As in any hydraulic system, air bubbles
make the fluid spongy, therefore, pressures will be
low and build up slowly.
Improper filling can also raise the fluid level too
high. When the transmssion has too much fluid, thegeartrain churns up foam and cause the same condi-
tions which occur with a low fluid level.
In either case, air bubbles can cause overheating
and/or fluid oxidation, and varnishing. This can
interfere with normal valve, clutch, and accumulator
operation. Foaming can also result in fluid escaping
from the transmission vent where it may be mis-
taken for a leak.
After the fluid has been checked, seat the dipstick
fully to seal out water and dirt.
The transmission has a dipstick to check oil level.
It is located on the right side of the engine. Be sure
to wipe all dirt from dipstick handle before removing.
Fluid level is checked with the engine running at
curb idle speed, the transmission in NEUTRAL and
the transmission fluid at normal operating tempera-
ture.The engine should be running at idle
speed for at least one minute, with the vehicle
on level ground.
The transmission fluid level can be checked two
ways.
PROCEDURE ONE
(1) Transmission fluid must be at normal operat-
ing temperature for accurate fluid level check. Drive
vehicle if necessary to bring fluid temperature up to
normal hot operating temperature of 82ÉC (180ÉF).
(2) Position vehicle on level surface.
(3) Start and run engine at curb idle speed.
(4) Apply parking brakes.
(5) Shift transmission momentarily into all gear
ranges. Then shift transmission back to NEUTRAL.
(6) Clean top of filler tube and dipstick to keep
dirt from entering tube.
(7) Remove dipstick (Fig. 87) and check fluid level
as follows:
(a) Correct acceptable level is in crosshatch area.
(b) Correct maximum level is to MAX arrow
mark.
(c) Incorrect level is at or below MIN line.
(d) If fluid is low, add only enough MopartAT F
+4 to restore correct level. Do not overfill.
Fig. 87 Dipstick Fluid Level Marks - Typical
1 - DIPSTICK
2 - MAXIMUM CORRECT FLUID LEVEL
3 - ACCEPTABLE FLUID LEVEL
21 - 202 AUTOMATIC TRANSMISSION - 48REDR
FLUID AND FILTER (Continued)

FLUID AND FILTER
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - EFFECTS OF
INCORRECT FLUID LEVEL
A low fluid level allows the pump to take in air
along with the fluid. Air in the fluid will cause fluid
pressures to be low and develop slower than normal.
If the transmission is overfilled, the gears churn the
fluid into foam. This aerates the fluid and causing
the same conditions occurring with a low level. In
either case, air bubbles cause fluid overheating, oxi-
dation and varnish buildup which interferes with
valve and clutch operation. Foaming also causes fluid
expansion which can result in fluid overflow from the
transmission vent or fill tube. Fluid overflow can eas-
ily be mistaken for a leak if inspection is not careful.
DIAGNOSIS AND TESTING - CAUSES OF
BURNT FLUID
Burnt, discolored fluid is a result of overheating
which has three primary causes.
(1) Internal clutch slippage, usually caused by low
line pressure, inadequate clutch apply pressure, or
clutch seal failure.
(2) A result of restricted fluid flow through the
main and/or auxiliary cooler. This condition is usu-
ally the result of a faulty or improperly installed
drainback valve, a damaged main cooler, or severe
restrictions in the coolers and lines caused by debris
or kinked lines.
(3) Heavy duty operation with a vehicle not prop-
erly equipped for this type of operation. Trailer tow-
ing or similar high load operation will overheat the
transmission fluid if the vehicle is improperly
equipped. Such vehicles should have an auxiliary
transmission fluid cooler, a heavy duty cooling sys-
tem, and the engine/axle ratio combination needed to
handle heavy loads.
DIAGNOSIS AND TESTING - FLUID
CONTAMINATION
Transmission fluid contamination is generally a
result of:
²adding incorrect fluid
²failure to clean dipstick and fill tube when
checking level
²engine coolant entering the fluid
²internal failure that generates debris
²overheat that generates sludge (fluid break-
down)
²failure to replace contaminated converter after
repairThe use of non-recommended fluids can result in
transmission failure. The usual results are erratic
shifts, slippage, abnormal wear and eventual failure
due to fluid breakdown and sludge formation. Avoid
this condition by using recommended fluids only.
The dipstick cap and fill tube should be wiped
clean before checking fluid level. Dirt, grease and
other foreign material on the cap and tube could fall
into the tube if not removed beforehand. Take the
time to wipe the cap and tube clean before withdraw-
ing the dipstick.
Engine coolant in the transmission fluid is gener-
ally caused by a cooler malfunction. The only remedy
is to replace the radiator as the cooler in the radiator
is not a serviceable part. If coolant has circulated
through the transmission, an overhaul is necessary.
The torque converter should also be replaced when-
ever a failure generates sludge and debris. This is
necessary because normal converter flushing proce-
dures will not remove all contaminants.
STANDARD PROCEDURE
STANDARD PROCEDURE - FLUID LEVEL
CHECK
Low fluid level can cause a variety of conditions
because it allows the pump to take in air along with
the fluid. As in any hydraulic system, air bubbles
make the fluid spongy, therefore, pressures will be
low and build up slowly.
Improper filling can also raise the fluid level too
high. When the transmssion has too much fluid, the
geartrain churns up foam and cause the same condi-
tions which occur with a low fluid level.
In either case, air bubbles can cause overheating
and/or fluid oxidation, and varnishing. This can
interfere with normal valve, clutch, and accumulator
operation. Foaming can also result in fluid escaping
from the transmission vent where it may be mis-
taken for a leak.
After the fluid has been checked, seat the dipstick
fully to seal out water and dirt.
The transmission has a dipstick to check oil level.
It is located on the right side of the engine. Be sure
to wipe all dirt from dipstick handle before removing.
The torque converter fills in both the P (PARK)
and N (NEUTRAL) positions. Place the selector lever
in P (PARK) to be sure that the fluid level check is
accurate.The engine should be running at idle
speed for at least one minute, with the vehicle
on level ground.At normal operating temperature
(approximately 82 C. or 180 F.), the fluid level is cor-
rect if it is in the HOT region (cross-hatched area) on
the oil level indicator. The fluid level will be approx-
21 - 366 AUTOMATIC TRANSMISSION - 45RFE/545RFEDR

HEATING & AIR CONDITIONING
TABLE OF CONTENTS
page page
HEATING & AIR CONDITIONING
DESCRIPTION
DESCRIPTION - ENGINE COOLING
SYSTEM REQUIREMENTS...............1
DESCRIPTION - HEATER AND AIR
CONDITIONER........................1
OPERATION - HEATER AND AIR
CONDITIONER........................1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - A/C
PERFORMANCE.......................3DIAGNOSIS AND TESTING - HEATER
PERFORMANCE TEST..................6
SPECIFICATIONS - A/C SYSTEM............7
CONTROLS.............................9
DISTRIBUTION..........................26
PLUMBING.............................41
HEATING & AIR
CONDITIONING
DESCRIPTION
DESCRIPTION - ENGINE COOLING SYSTEM
REQUIREMENTS
To maintain the performance level of the heating,
ventilation and air conditioning (HVAC) system, the
engine cooling system must be properly maintained.
The use of a bug screen is not recommended. Any
obstructions in front of the radiator or A/C condenser
will reduce the performance of the A/C and engine
cooling systems.
The engine cooling system includes the radiator,
thermostat, radiator hoses and the engine coolant
pump. Refer to Cooling for more information before
opening or attempting any service to the engine cool-
ing system.
DESCRIPTION - HEATER AND AIR
CONDITIONER
A manually controlled single zone type heating-air
conditioning system or a manually controlled dual
zone type heating-air conditioning system is available
on this model.
All vehicles are equipped with a common heater,
ventilation and air conditioning (HVAC) housing (Fig.
1). The system combines air conditioning, heating,
and ventilating capabilities in a single unit housing
mounted within the passenger compartment under
the instrument panel. The HVAC housing includes:
²Blower motor
²Blower motor resistor block²Heater core
²Evaporator coil
²Blend door and actuator
²Defrost door and actuator
²Mode door and actuator
²Recirculation door and actuator
Based upon the system and mode selected, condi-
tioned air can exit the HVAC housing through one or
a combination of the three main housing outlets:
defrost, panel or floor. The defrost outlet is located on
the top of the housing, the panel outlet is located on
the face of the housing and the floor outlet is located
on the bottom of the housing. Once the conditioned
air exits the unit housing, it is further directed
through molded plastic ducts to the various outlets in
the vehicle interior. These outlets and their locations
are as follows:
²Defroster Outlet- A single large defroster out-
let is located in the center of the instrument panel
top cover, near the base of the windshield.
²Side Window Demister Outlets- There are
two side window demister outlets, one is located at
each outboard end of the instrument panel top cover,
near the belt line at the A-pillars.
²Panel Outlets- There are four panel outlets in
the instrument panel, one located near each outboard
end of the instrument panel facing the rear of the
vehicle and two located near the top of the instru-
ment panel center bezel.
²Front Floor Outlets- There are two front floor
outlets, one located above each side of the floor panel
center tunnel near the dash panel.
OPERATION - HEATER AND AIR CONDITIONER
The heating and air conditioning systems pulls
outside (ambient) air through the cowl opening at the
base of the windshield, then into the plenum cham-
DRHEATING & AIR CONDITIONING 24 - 1

Condition Possible Causes Correction
Normal pressures, but A/C
Performance Test air
temperatures at center panel
outlet are too high.1. Excessive refrigerant oil in
system.1. See Refrigerant Oil Level in this group.
Recover the refrigerant from the refrigerant
system and inspect the refrigerant oil content.
Restore the refrigerant oil to the proper level, if
required.
2. Blend door inoperative or
sealing improperly.2. See Blend Door in this group. Inspect the
blend door for proper operation and sealing and
correct, if required.
3. Blend door actuator faulty
or inoperative.3. Perform blend door actuator diagnosis, replace
if faulty.
The low side pressure is
normal or slightly low, and the
high side pressure is too low.1. Low refrigerant system
charge.1. See Refrigerant System Leaks in this group.
Test the refrigerant system for leaks. Repair,
evacuate and charge the refrigerant system, if
required.
2. Refrigerant flow through
the accumulator is restricted.2. See Accumulator in this group. Replace the
restricted accumulator, if required.
3. Refrigerant flow through
the evaporator coil is
restricted.3. See A/C Evaporator in this group. Replace the
restricted evaporator coil, if required.
4. Faulty compressor. 4. See A/C Compressor in this group. Replace
the compressor, if required.
The low side pressure is
normal or slightly high, and
the high side pressure is too
high.1. Condenser air flow
restricted.1. Check the A/C 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. See 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. See 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.
The low side pressure is too
high, and the 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. Fixed orifice tube not
installed.2. See A/C Orifice Tube in this group. Replace
the liquid line, if required.
3. Faulty compressor. 3. See A/C Compressor in this group. Replace
the compressor, if required.
DRHEATING & AIR CONDITIONING 24 - 5
HEATING & AIR CONDITIONING (Continued)

Condition Possible Causes Correction
The low side pressure is too
low, and the high side
pressure is too high.1. Restricted refrigerant flow
through the refrigerant lines.1. See Liquid, Suction, and Discharge Line 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 fixed orifice tube.2. See A/C Orifice Tube in this group. Replace
the liquid line, if required.
3. Restricted refrigerant flow
through the condenser.3. See A/C Condenser in this group. Replace the
restricted condenser, if required.
DIAGNOSIS AND TESTING - HEATER
PERFORMANCE TEST
Review Safety Warnings and Cautions before per-
forming this procedure (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - WARNING) and
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - CAUTION).
Check the coolant level, drive belt tension, vacuum
line connections, radiator air flow and fan operation.
Start engine and allow to warm up to normal tem-
perature.
WARNING: DO NOT REMOVE RADIATOR CAP
WHEN ENGINE IS HOT, PERSONAL INJURY CAN
RESULT.
If vehicle has been run recently, wait 15 minutes
before removing cap. Place a rag over the cap andturn it to the first safety stop. Allow pressure to
escape through the overflow tube. When the system
stabilizes, remove the cap completely.
MAXIMUM HEATER OUTPUT: TEST AND ACTION
Engine coolant is provided to the heater system by
two heater hoses. With the engine idling at normal
operating temperature, set the temperature control
to maximum heat, the mode control to the floor posi-
tion, and the blower in the highest speed position.
Using a test thermometer, check the temperature of
the air being discharged from the floor outlets. Com-
pare the test thermometer reading to the Tempera-
ture Reference chart.
TEMPERATURE REFERENCE CHART
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)
Both of the heater hoses should be HOT to the
touch (coolant return hose should be slightly cooler
than the supply hose). If the coolant return hose is
much cooler than the supply hose, locate and repair
the engine coolant flow obstruction in the heater sys-
tem. If both heater hoses are cool to the touch,
inspect the engine cooling system (Refer to 7 -
COOLING - DIAGNOSIS AND TESTING).
OBSTRUCTED COOLANT FLOW Possible loca-
tions or causes of obstructed coolant flow are as fol-
lows:
²Pinched or kinked heater hoses.
²Improper heater hose routing.
²Plugged heater hoses or supply and return ports
at the cooling system connections.
²Plugged heater core.If proper coolant flow through the cooling system is
verified, and heater outlet air temperature is insuffi-
cient, a mechanical problem may exist.
MECHANICAL PROBLEMS Possible causes of
insufficient heat due to mechanical problems are as
follows:
²Obstructed cowl air intake.
²Obstructed heater system outlets.
²Blend door not functioning properly.
TEMPERATURE CONTROL
If the heater outlet air temperature cannot be
adjusted with the temperature control knob on the
A/C-heater control, the following could require ser-
vice:
²Blend door binding.
²Faulty blend door motor.
24 - 6 HEATING & AIR CONDITIONINGDR
HEATING & AIR CONDITIONING (Continued)