DUCT-INSTRUMENT PANEL DEMISTER
REMOVAL
WARNING: On vehicles equipped with airbags, disable the airbag system before attempting any steering
wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the
battery negative (ground) cable, then wait two minutes for the airbag system capacitor to discharge before
performing further diagnosis or service. This is the only sure way to disable the airbag system. Failure to
take the proper precautions could result in an accidental airbag deployment and possible personal injury or
death.
NOTE: Take the proper precautions to protect the instrument panel from cosmetic damage.
1. Remove the instrument panel and place it on a
workbench (Refer to 23 - BODY/INSTRUMENT
PANEL/INSTRUMENT PANEL ASSEMBLY -
REMOVAL).
2. Remove the radio (Refer to 8 - ELECTRICAL/AU-
DIO/RADIO - REMOVAL).
3. Remove the defroster duct (Refer to 24 - HEATING
& AIR CONDITIONING/DISTRIBUTION/DUCT-DE-
FROSTER - REMOVAL).
4. Remove the two screws (1) that secure the center
distribution duct (2) to the instrument panel support
(3) and remove the duct.
5. Disconnect the right side instrument panel duct
adapter (2) from the right side instrument panel
duct (1) and remove the adapter.
6. Remove the screw that secures each intermediate
demister duct (3 and 4) to the instrument panel
cover.
7. Disconnect the intermediate demister ducts from
the demister ducts and remove the intermediate
ducts.
8. Disconnect the left side instrument panel duct
adapter (6) from the right side instrument panel
duct (5) and remove the adapter
9. Remove the instrument panel cover (Refer to 23 -
BODY/INSTRUMENT PANEL/COVER-INSTRU-
MENT PANEL - REMOVAL).
10. Remove the two screwsthat secure each demis-
ter duct to the instrument panel cover and remove
the ducts.
HOUSING-HVAC
DESCRIPTION
All models are equipped with a common HVAC housing assembly that combines A/C and heating capabilities into a
single unit mounted within the passenger compartment. The HVAC housing assembly consists of the following:
HVAC housing— The HVAC housing consists of an upper housing (7) and a lower housing (10) that are
attached together by screws and is mounted to the dash panel behind the instrument panel. The HVAC hous-
ing contains the heater core (9), A/C evaporator (15), blend-air and mode-air doors, and has mounting provi-
sions for the air-door actuators (3, 5, 6 and 8), floor distribution duct (4), blower motor (13), blower motor
resistor, foam seals (12, 14 and 16) and the HVAC wire harness (11).
Air inlet housing— The air inlet housing (1) is mounted to the right end of the HVAC housing andcontains
the recirculation-air door and has mounting provisions for the recirculation door actuator (2).
The heating-A/C system is a blend-air type system. The blend-air doors control the amount of conditioned air that is
allowed to flow through, or around, the heater core. The dual zone heating A/C system uses two blend door actua-
tors while the single zone system uses only one blend door actuator.
The A/C system is designed for the use of a non-CFC, R-134a refrigerant and uses an A/C evaporator to cool and
dehumidify the incoming air prior to blending it with the heated air. A temperature control determines the discharge
air temperature by operating the blend door actuator(s), which moves the blend-air door(s). This allows an almost
immediate control of the output air temperature of the system. The mode door actuator operates the mode-air doors
which direct the flow of the conditioned air out the various air outlets, depending on the mode selected. The recir-
culation door actuator operates the recirculation-air door which closesoff the fresh air intake and recirculates the air
already inside the vehicle. The electric door actuators are connected to the vehicle electrical system by the HVAC
wire harness. The blower motor controls the velocity of air flowing through the HVAC housing assembly by spinning
the blower wheel within the HVAC housings at the selected speed by use of theblower motor resistor.
The HVAC housing must be removed from the vehicle and disassembled for service of the heater core, A/C evap-
orator, evaporator temperature sensor, blend-air and mode-air doors. The air inlet housing must be removed from
HVAC housing and disassembled for service of the recirculation-air door.
REMOVAL
HVAC HOUSING ASSEMBLY
WARNING: Refer to the applicable warnings and cautions for this system before performing the following
operation (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - WARNINGS) and (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - CAUTIONS). Failure to follow the warnings and cautions could result
in possible personal injury or death.
WARNING: On vehicles equipped with airbags, disable the airbag system before attempting any steering
wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the
negative battery (ground) cable, then wait two minutes for the airbag system capacitor to discharge before
performing further diagnosis or service. This is the only sure way to disable the airbag system. Failure to
take the proper precautions could result in accidental airbag deploymentand possible personal injury or
death.
NOTE: The HVAC housing must be removedfrom the vehicle and disassembled for service of the A/C evap-
orator, evaporator temperature sensor, mode-air and blend-air doors.
1. Recover the refrigerant from the refrigerant system
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - STANDARD PROCEDURE -
REFRIGERANT SYSTEM RECOVERY).
2. Drain the engine cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE - COOL-
ING SYSTEM DRAIN).
3. Disconnect and isolate the negative battery cable.
4. Disconnect the A/C liquid line and the A/C accumu-
lator from the A/C evaporator (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING/LINE-A/C
LIQUID - REMOVAL) and (Refer to 24 - HEATING
& AIR CONDITIONING/PLUMBING/ACCUMULA-
TOR-A/C - REMOVAL).
5. Disconnect the heater hoses from the heater core
tubes.
6. Remove the powertrain control module (PCM) to
gain access to the two nuts (3) that secure the
HVAC housing (1) to the engine compartment side of the dash panel (2) and remove the nuts (Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MODULES/POWERTRAIN CONTROL MODULE - REMOVAL).
7. On Mega Cab models, remove the floor console
duct (Refer to 24 - HEATING & AIR CONDITION-
ING/DISTRIBUTION/DUCT-FLOOR CONSOLE -
REMOVAL).
8. Remove the instrument panel from the passenger
compartment (Refer to 23 - BODY/INSTRUMENT
PANEL ASSEMBLY - REMOVAL).
9. Remove the bolt (5) that secures the HVAC hous-
ing (4) to the floor bracket (6).
10. Remove the two nuts (3 and 7) that secure the
HVAC housing to the passenger compartment
side of the dash panel (1).
11. Pull the HVAC housing assembly rearward and
remove the housing assembly from the passenger
compartment.
12. If required, remove the fresh air inlet (2) from the
dash panel (1).
AIR INLET HOUSING
WARNING: Refer to the applicable warnings and cautions for this system before performing the following
operation (Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - WARNINGS) and (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - CAUTIONS). Failure to follow the warnings and cautions could result
in possible personal injury or death.
WARNING: On vehicles equipped with airbags, disable the airbag system before attempting any steering
wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the
negative battery (ground) cable, then wait two minutes for the airbag system capacitor to discharge before
performing further diagnosis or service. This is the only sure way to disable the airbag system. Failure to
take the proper precautions could result in accidental airbag deploymentand possible personal injury or
death.
NOTE: The air inlet housing must be removed from HVAC housing and disassembled for service of the
recirculation-air door.
1. Remove the HVAC housing assembly (Refer to 24
- HEATING & AIR CONDITIONING/DISTRIBU-
TION/HOUSING-HVAC - HVAC HOUSING ASSEM-
BLY - REMOVAL).
2. Remove the recirculation door actuator (1) from the
air inlet housing (2) and disconnect the HVAC wire
harness (4) from the actuator.
3. Remove the two screws (3) that secure the rear of
the air inlet housing to the top of the HVAC housing
(5).
MOTOR-BLOWER
DESCRIPTION
The blower motor (1) is used to control the velocity of
air moving through the HVAC housing by spinning the
blower wheel (3) within the HVAC air inlet housing at
the selected speed.
The blower motor is a 12-volt, direct current (DC)
motormountedwithinaplastichousingwithaninte-
gral wire harness connector (2) and squirrel cage-type
blower wheel (3) that is secured to the blower motor
shaft (4). The blower wheel is positioned within the air
inlet housing on the passenger side end of the HVAC
housing.
OPERATION
The blower motor is used to control the velocity of air moving through the HVAC housing by spinning the blower
wheel within the HVAC air inlet housing at the selected speed.
The blower motor will operate whenever the ignition switch is in the Run position and the blower motor control is in
any position except Off. The blower motor receives battery current through the totally integrated power module
(TIPM) whenever the ignition switch is in the Run position.
Blower motor speed is controlled by regulating the ground path through or around the blower motor resistor and
through the blower motor control located within the A/C-heater control.
The blower motor can be accessed for service from underneath the instrument panel.
NOTE: The blower motor is supplied with a 12V feed from the TIPM, through theresistor block, whenever
the ignition switch is in the RUN position. Due to an open circuit conditionwithin the blower motor control
switch the TIPM is UNABLE to detect an OPEN circuit for the blower motor.
The blower motor control system is diagnosed using a scan tool (Refer to 24 -HVAC Electrical Diagnostics for more
information).
The blower motor and blower wheel are factory balanced and cannot be adjusted or repaired. If faulty or damaged,
the blower motor and wheel must be replaced as an assembly.
DIAGNOSIS AND TESTING
BLOWER MOTOR
WARNING: On vehicles equipped with airbags, disable the airbag system before attempting any steering
wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the
negative battery (ground) cable, then wait two minutes for the airbag system capacitor to discharge before
performing further diagnosis or service. Failure to take the proper precautions could result in accidental
airbag deployment and possible personal injury or death.
NOTE: The blower motor is supplied with a 12V feed from the TIPM, through theresistor block, whenever
the ignition switch is in the RUN position. Due to an open circuit conditionwithin the blower motor control
switch the TIPM is UNABLE to detect an OPEN circuit for the blower motor.
To determine if an open condition exists within the blower motor circuit wiring, it is necessary to disconnect the
negative battery cable and check for continuity within the blower motor circuits using an ohmmeter. For circuit
descriptions and diagrams, refer to Air Conditioning/Heater in Group 8W -Wiring Diagrams.
OPERATION
Possible causes of the blower motor not operating include:
Faulty blower motor
Faulty blower motor circuit wiring or wire harness connectors
Faulty blower motor control
Possible causes of the blower motor not operating in one or more speeds include:
Faulty blower motor resistor
Faulty blower motor circuit wiring or wire harness connectors
Faulty blower motor control
VIBRATION
Possible causes of blower motor vibration include:
Improper blower motor mounting
Improper blower wheel mounting
Deformed blower wheel
Out of balance blower wheel due to foreign material in the wheel
Faulty blower motor
NOISE
To determine if the blower motor is the source of the noise, simply switch the blower motor from Off to On. To verify
that the blower motor is the source of the noise, unplug the blower motor wire harness connector and operate the
heating-A/C system. If the noise goes away, possible causes include:
Foreign material in the HVAC air inlet housing
Improper blower motor mounting
Improper blower wheel mounting
Faulty blower motor
CORE-HEATER
DESCRIPTION
The heater core (1) is a heat exchanger made of rows
of tubes and fins. The heater core is positioned within
the HVAC housing through the panel (2) located at the
front of the HVAC housing. The heater core tubes (3)
are attached to the front of the heater core and are
secured to the HVAC housing by a bracket.
The heater core can be serviced by removing the
HVAC housing assembly from the vehicle.
OPERATION
Engine coolant is circulated through the heater hoses to the heater core atall times. As the coolant flows through
the heater core, heat is removed from the engine and is transferred to the heater core tubes and fins. Air directed
through the heater core picks up the heat from the heater core fins. The blend-air door(s) allows control of the
heater output air temperature by regulating the amount of air flowing through the heater core. The blower motor
speed controls the volume of air flowing through the HVAC housing.
The heater core cannot be repaired and, if faulty or damaged, it must be replaced.
REMOVAL
WARNING: On vehicles equipped with airbags, disable the airbag system before attempting any steering
wheel, steering column, or instrument panel component diagnosis or service. Disconnect and isolate the
negative battery (ground) cable, then wait two minutes for the airbag system capacitor to discharge before
performing further diagnosis or service. This is the only sure way to disable the airbag system. Failure to
take the proper precautions could result in accidental airbag deploymentand possible personal injury or
death.
NOTE: Disassembly of the HVAC housing is not required to remove heater core.