Page 5085 of 5267

The A/C-heater control is diagnosed using a scan tool (Refer to 24 - HEATING& AIR CONDITIONING - DIAGNO-
SIS AND TESTING and to 24 - HVAC Electrical Diagnostics for more information).
The A/C-heater control cannot be repaired and, if faulty or damaged, it must be replaced. The illumination lamps for
the A/C-heater control are available for service replacement.
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: Single zone A/C-heater control shown. Dual
zone similar.
1. Disconnect and isolate the negative battery cable.
2. Remove the center bezel (1) from the instrument
panel and disconnect the wire harness connectors
(4 and 5) from the back of the A/C-heater control
(2) (Refer to 23 - BODY/INSTRUMENT PANEL/IN-
STRUMENT PANEL CENTER BEZEL -
REMOVAL).
NOTE: Take the proper precautions to protect the
front face of the center bezel from cosmetic dam-
age.
3. Place the center bezel on a workbench and
remove the four screws (3) that secure the A/C-
heater control to the center bezel and remove the
control.
INSTALLATION
NOTE: Single zone A/C-heater control shown. Dual
zone similar.
1. Position the A/C-heater control (2) into the back of
the instrument panel center bezel (1).
2. Install the four screws (3) that secure the A/C-
heater control to the center bezel. Tighten the
screws to 2.2 Nꞏm (20 in. lbs.).
3. Connect the wire harness connectors (4 and 5) to
the back of the A/C-heater control and install the
instrument panel center bezel (Refer to 23 - BODY/
INSTRUMENT PANEL/INSTRUMENT PANEL CEN-
TER BEZEL - INSTALLATION).
4. Reconnect the negative battery cable.
Page 5089 of 5267

SENSOR-EVAPORATOR TEMPERATURE
DESCRIPTION
The evaporator temperature sensor is a two-wire tem-
perature sensing element located at the coldest point
on the face of the A/C evaporator. The probe (1) for
evaporator temperature sensor is attached to the
evaporator coil fins. The wire lead (2) for evaporator
temperature sensor is routed through an opening at
the back of the HVAC housing and the connector (3)
is attached to the HVAC wire harness.
OPERATION
The evaporator temperature sensor monitors the surface temperature of A/C evaporator and supplies an input signal
to the A/C-heater control. The A/C-heater control uses the evaporator temperature sensor input signal to optimize
A/C system performance and to protect the A/C system from evaporator freezing. The evaporator temperature sen-
sor will change its internal resistance in response to the temperatures itmonitors and is connected to the A/C-heater
control through sensor ground circuit and a 5-volt reference signal circuit. As the temperature of the A/C evaporator
decreases, the internal resistance of the evaporator temperature sensordecreases.
The A/C-heater control uses the monitored voltage reading as an indication of evaporator temperature. The A/C-
heater control is programmed to respond to this input by requesting the powertrain control module (PCM) or the
engine control module (ECM) (depending on engine application) to cycle the A/C compressor clutch as necessary to
optimize A/C system performance and to protect the A/C system from evaporatorfreezing(Referto24-HEATING
& AIR CONDITIONING/CONTROLS/COIL-A/C COMPRESSOR CLUTCH - OPERATION formore information).
The evaporator temperature sensor is diagnosed using a scan tool (Refer to24 - HEATING & AIR CONDITIONING
- DIAGNOSIS AND TESTING and to 24 - HVAC Electrical Diagnostics for more information).
The evaporator temperature sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
Page 5090 of 5267
REMOVAL
1. RemovetheHVAChousingandplaceitonawork-
bench (Refer to 24 - HEATING & AIR CONDITION-
ING/DISTRIBUTION/HOUSING-HVAC -
REMOVAL).
2. Remove the wire lead for the evaporator tempera-
ture sensor (2) from the retainer located on the
HVAC housing (1) and disconnect the sensor con-
nector from the HVAC wire harness (3).
3. Remove the lower half of the HVAC housing from
the upper half of the HVAC housing to gain access
to the A/C evaporator (Refer to 24 - HEATING &
AIR CONDITIONING/DISTRIBUTION/HOUSING-
HVAC - DISASSEMBLY).
4. Carefully remove the probe of the evaporator tem-
perature sensor (1) from the fins of the A/C evap-
orator (2).
5. Remove the wire lead of the evaporator tempera-
ture sensor (3) from the upper half of the HVAC
housing (4).
Page 5091 of 5267
INSTALLATION
1. Install the probe of the evaporator temperature
sensor (1) between the fins of the A/C evaporator
(2).
2. Route the wire lead for the evaporator temperature
sensor (3) into the opening located on the upper
half of the HVAC housing (4).
3. Assemble the HVAC housing (Refer to 24 - HEAT-
ING & AIR CONDITIONING/DISTRIBUTION/
HOUSING-HVAC - ASSEMBLY).
4. Install the wire lead of the evaporator temperature
sensor (2) to the retainer located on the HVAC
housing (1) and connect the sensor connector to
theHVACwireharness(3).
5. Install the HVAC housing (Refer to 24 - HEATING
& AIR CONDITIONING/DISTRIBUTION/HOUSING-
HVAC - INSTALLATION).
Page 5098 of 5267

DUCT-FLOOR DISTRIBUTION
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: Regular Cab model shown. Other models
similar.
1. Remove the HVAC housing from the vehicle (Refer
to 24 - HEATING & AIR CONDITIONING/DISTRI-
BUTION/HOUSING-HVAC - REMOVAL).
2. Remove the screws (3) that secure the floor distri-
bution duct (1) to the bottom of the HVAC housing
(2).
3. Remove the floor distribution duct from the HVAC
housing.
INSTALLATION
NOTE: Regular Cab model shown. Other models
similar.
1. Position the floor distribution duct (1) onto the bot-
tom of the HVAC housing (2).
2. Install the screws (3) that secure the floor distribu-
tion duct to the HVAC housing. Tighten the screws
to 2.2 Nꞏm (20 in. lbs.).
3. Install the HVAC housing (Refer to 24 - HEATING
& AIR CONDITIONING/DISTRIBUTION/HOUSING-
HVAC - INSTALLATION).
Page 5099 of 5267

DUCT-INSTRUMENT PANEL
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 three screws that secure each instru-
ment panel duct to the instrument panel support
and remove the ducts.
Page 5100 of 5267

INSTALLATION
1. Position the instrument panel ducts (1 and 5) onto
the instrument panel support.
2. Install the three screws that secure each instru-
ment panel duct to the instrument panel support.
Tighten the screws to 2.2 Nꞏm (20 in. lbs.).
3. Install the instrument panel cover (Refer to 23 -
BODY/INSTRUMENT PANEL/COVER-INSTRU-
MENT PANEL - INSTALLATION).
4. Position the left side instrument panel duct adapter
(6) into the instrument panel and connect it to the
left panel duct.
5. Position the intermediate demister ducts (3 and 4)
into the instrument panel and connect them to the
demister ducts.
6. Install the screw that secures each intermediate
demister duct to the instrument panel cover.
Tighten the screws to 2.2 Nꞏm (20 in. lbs.).
7. Position the right side instrument panel duct
adapter (2) into the instrument panel and connect it to the right panel duct.
8. Position the center distribution duct (2) to the
instrument panel support (3).
9. Install the two screws (1) that secure the center
distribution duct to the instrument panel support.
Tighten the screws to 2.2 Nꞏm (20 in. lbs.).
10. Install the defroster duct (Refer to 24 - HEATING
& AIR CONDITIONING/DISTRIBUTION/DUCT-
DEFROSTER - INSTALLATION).
11. Install the radio (Refer to 8 - ELECTRICAL/AU-
DIO/RADIO - INSTALLATION).
12. Install the instrument panel (Refer to 23 - BODY/
INSTRUMENT PANEL/INSTRUMENT PANEL
ASSEMBLY - INSTALLATION).
Page 5101 of 5267

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.