Scheme 279
DESCRIPTION
The blend door actuator (1) is a reversible, 12 volt direct current (DC), servo motor. The blend door actuator is located on the top of the HVAC housing. The blend door actuator is interchangeable with the actuators for both mode-air doors and the recirculation-air door. Each actuator is contained within an identical black molded plastic housing with an integral wire connector receptacle. Three integral mounting tabs allow the actuator to be secured to the HVAC housing. Each actuator also has an identical output shaft with splines that connects it to the blend-air door. The blend door actuator does require mechanical indexing to the blend-air door, as it is electronically calibrated by the A/C-heater control.
Scheme 280
OPERATION
The blend door actuator is connected to the A/C-heater control through the vehicle electrical system by a dedicated two-wire lead and connector of the HVAC wire harness. The blend door actuator can move the blend-air door in two directions. When the A/C-heater control pulls the voltage on one side of the motor connection high and the other connection low, the blend-air door will move in one direction. When the A/C-heater control reverses the polarity of the voltage to the motor, the blend-air door moves in the opposite direction.
When the A/C-heater control makes the voltage to both connections high or both connections low, the blend-air door stops and will not move. The A/C-heater control uses a pulse-count positioning system to monitor the operation and relative position of the blend door actuator and the blend-air door. The A/C-heater control learns the blend-air door stop positions during the calibration procedure and will store a diagnostic trouble code (DTC) for any problems it detects in the blend door actuator circuit.
The blend door actuator cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
The blend door actuator is diagnosed using the scan tool. Refer to HVAC - ELECTRICAL DIAGNOSTICS for more information.
Scheme 281
- Disconnect and isolate the negative battery cable.
- Remove the instrument panel assembly (Refer to «ASSEMBLY-INSTRUMENT PANEL»(ref-212841-S41548306542005122700000) ).
- Remove the screws (4) that secure the blend door actuator (2) to the top of the HVAC housing (3).
- Disconnect the HVAC wire harness connector (1) from the blend door actuator.
- Remove the blend door actuator from the HVAC housing.
Scheme 282
Scheme 283
- Position the blend door actuator (1) onto the top of the HVAC housing (2). If necessary, rotate the actuator slightly to align the splines on the actuator output shaft (3) with those on the blend-air door linkage (4).
- Install the screws (4) that secure the blend door actuator (2) to the HVAC housing (3). Tighten the screws to 2 N.m (17 in. lbs.).
- Connect the HVAC wire harness connector (1) to the blend door actuator.
- Install the instrument panel assembly (Refer to «ASSEMBLY-INSTRUMENT PANEL»(ref-212841-S41548306542005122700000) ).
- Reconnect the negative battery cable.
- Initiate the Actuator Calibration function using a scan tool. Refer to HVAC System Test, found in «HVAC - ELECTRICAL DIAGNOSTICS»(ref-212849) .
The two mode door actuators (floor/defrost and panel door) (1) are reversible, 12-volt direct current (DC), servo motors. Both mode door actuators are located near the drivers side end of the HVAC housing. The mode door actuators are mechanically connected to the floor/defrost and the panel-air door. Both mode door actuators are interchangeable with each other and with the actuators for the blend-air door and the recirculation-air door. Each actuator is contained within an identical black molded plastic housing with an integral wire connector receptacle. Three integral mounting tabs allow the actuator to be secured to the top of the HVAC housing. Each actuator also has an identical output shaft with splines that connects it to the mode-air doors. The mode door actuators do not require mechanical indexing to the mode-air doors, as they are electronically calibrated by the A/C-heater control.
Scheme 284
The floor/defrost and panel (mode) door actuators are connected to the A/C-heater control through the vehicle electrical system by a dedicated two-wire lead and connector of the HVAC wire harness. The mode door actuators can move the floor/defrost and the panel-air doors in two directions. When the A/C-heater control pulls the voltage on one side of the motor connection high and the other connection low, the mode-air door(s) will move in one direction. When the A/C-heater control reverses the polarity of the voltage to the motor, the mode-air door(s) moves in the opposite direction.
When the A/C-heater control makes the voltage to both connections high or both connections low, the mode-air door(s) stops and will not move. The A/C-heater control uses a pulse-count positioning system to monitor the operation and relative position of the floor/defrost and panel door actuators and the mode-air doors. The A/C-heater control learns the mode-air door stop positions during the calibration procedure and will store a diagnostic trouble code (DTC) for any problems it detects in the mode door actuator circuits.
The mode door actuators cannot be adjusted or repaired and, if faulty or damaged, they must be replaced.
The mode door actuators are diagnosed using a scan tool. Refer to HVAC - ELECTRICAL DIAGNOSTICS for more information.
The recirculation door actuator (1) is a reversible, 12 volt direct current (DC), servo motor. The recirculation door actuator is located on the left side of the HVAC air inlet housing. The recirculation door actuator is interchangeable with the actuators for the blend-air door and the mode-air doors. Each actuator is contained within an identical black molded plastic housing with an integral wire connector receptacle. Three integral mounting tabs allow the actuator to be secured to the air inlet housing. Each actuator also has an identical output shaft with splines that connects it to the recirculation-air door. The recirculation door actuator does not require mechanical indexing to the recirculation-air door, as it is electronically calibrated by the A/C-heater control.
Scheme 285
The recirculation door actuator is connected to the A/C-heater control through the vehicle electrical system by a dedicated two-wire lead and connector of the HVAC wire harness. The recirculation door actuator can move the recirculation-air door in two directions. When the A/C-heater control pulls the voltage on one side of the motor connection high and the other connection low, the recirculation-air door will move in one direction. When the A/C-heater control reverses the polarity of the voltage to the motor, the recirculation-air door moves in the opposite direction.
When the A/C-heater control makes the voltage to both connections high or both connections low, the recirculation-air door stops and will not move. The A/C-heater control uses a pulse-count positioning system to monitor the operation and relative position of the recirculation door actuator and the recirculation-air door. The A/C-heater control learns the recirculation-air door stop positions during the calibration procedure and will store a diagnostic trouble code (DTC) for any problems it detects in the recirculation door actuator circuits.
The recirculation door actuator cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
The recirculation door actuator is diagnosed using a scan tool. Refer to HVAC - ELECTRICAL DIAGNOSTICS for more information.
Scheme 286
- Disconnect and isolate the negative battery cable.
- Remove the HVAC assembly (Refer to «HOUSING-HVAC»(ref-212853-S30259552272005122700000) ).
- Remove the air inlet housing (1) from the HVAC housing and place it on a workbench (Refer to «HOUSING-HVAC»(ref-212853-S30259552272005122700000) ).
- Remove the screws (2) that secure the recirculation door actuator (3) to the HVAC air inlet housing.
- Remove the recirculation door actuator from the HVAC air inlet housing.
Scheme 287
Scheme 288
- Position the recirculation door actuator (1) to the HVAC air inlet housing. If necessary, rotate the actuator slightly to align the splines on the actuator output shaft with those in the recirculation-air door linkage.
- Install the screws (2) that secure the recirculation door actuator (3) to the HVAC air inlet housing (1). Tighten the screws to 2 N.m (17 in. lbs.).
- Install the air inlet housing to the HVAC housing (Refer to «HOUSING-HVAC»(ref-212853-S30259552272005122700000) ).
- Install the HVAC housing (Refer to «HOUSING-HVAC»(ref-212853-S30259552272005122700000) ).
- Reconnect the negative battery cable.
- Initiate the Actuator Calibration function using a scan tool. Refer to HVAC System Test, found in «HVAC - ELECTRICAL DIAGNOSTICS»(ref-212849) .
The A/C compressor clutch assembly consists of a stationary electromagnetic A/C clutch field coil (4), pulley bearing and pulley assembly (3), clutch plate (2) and shims (7). These components provide the means to engage and disengage the A/C compressor from the engine accessory drive belt.
The A/C clutch field coil and the pulley bearing and pulley assembly are both retained on the nose of the A/C compressor with snap rings (5 and 6). The clutch plate is splined to the compressor shaft and secured with a bolt (1).
Scheme 289
The A/C compressor clutch components provide the means to engage and disengage the A/C compressor from the engine accessory drive belt. When the electromagnetic A/C clutch field coil is energized, it magnetically draws the clutch plate into contact with the clutch pulley and drives the compressor shaft. When the coil is not energized, the pulley freewheels on the clutch hub bearing, which is part of the pulley.
The A/C compressor clutch engagement is controlled by the following components
- A/C-heater control in the passenger compartment
- A/C pressure transducer on the A/C discharge line
- Powertrain control module (PCM) in the engine compartment
- A/C clutch relay in the power distribution center (PDC)
The A/C compressor clutch components cannot be repaired and, if faulty or damaged, they must be replaced.
A blower motor power module is used on this model when it is equipped with the automatic temperature control (ATC) heating-A/C system. Models equipped with the manual temperature control (MTC) heating-A/C system use a blower motor resistor block, instead of the blower motor power module (Refer to DESCRIPTION ).
The blower motor power module is mounted to the rear of the HVAC housing, directly behind the glove box. The blower motor power module consists of a molded plastic mounting plate with two integral connector receptacles (1). Concealed behind the mounting plate is the power module electronic circuitry and a large finned heat sink (2). The blower motor power module is accessed for service from beneath the right side of the instrument panel.
Scheme 290
The blower motor power module is connected to the vehicle electrical system through a dedicated lead and connector of the HVAC wire harness, A second connector receptacle receives the wire harness connector from the blower motor. The blower motor power module allows the microprocessor-based automatic temperature control (ATC) A/C-heater control to calculate and provide infinitely variable blower motor speeds based upon either manual blower switch input or the ATC programming using a pulse width modulated (PWM) circuit strategy.
The PWM voltage is applied to a comparator circuit which compares the PWM signal voltage to the blower motor feedback voltage. The resulting output drives the power module circuitry, which provides a linear output voltage to change or maintain the desired blower speed.
The blower motor power module cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
The blower motor power module is diagnosed using a scan tool. Refer to HVAC - ELECTRICAL DIAGNOSTICS for more information.
The A/C clutch relay is a International Standards Organization (ISO) micro-relay. Relays conforming to the ISO specifications have common physical dimensions, current capacities, terminal patterns, and terminal functions. The ISO micro-relay terminal functions are the same as a conventional ISO relay. However, the ISO micro-relay terminal pattern (or footprint) is different, the current capacity is lower, and the physical dimensions are smaller than those of the conventional ISO relay.
The A/C clutch relay is located in the power distribution center (PDC) in the engine compartment. Refer to the PDC label for A/C clutch relay identification and location.
Scheme 291
The black, molded plastic case is the most visible component of the A/C clutch relay. Five male spade-type terminals extend from the bottom of the base to connect the relay to the vehicle electrical system, and the ISO designation for each terminal is molded into the base adjacent to each terminal. The ISO terminal designations are as follows
- 30 (Common Feed) - This terminal is connected to the movable contact point of the relay.
- 85 (Coil Ground) - This terminal is connected to the ground feed side of the relay control coil.
- 86 (Coil Battery) - This terminal is connected to the battery feed side of the relay control coil.
- 87 (Normally Open) - This terminal is connected to the normally open fixed contact point of the relay.
- 87A (Normally Closed) - This terminal is connected to the normally closed fixed contact point of the relay.
The A/C clutch relay is an electromechanical switch that uses a low current input from the powertrain control module (PCM) to control the high current output to the A/C clutch electromagnetic field coil. The movable common feed contact point is held against the fixed normally closed contact point by spring pressure. When the relay coil is energized, an electromagnetic field is produced by the coil windings. This electromagnetic field draws the movable relay contact point away from the fixed normally closed contact point, and holds it against the fixed normally open contact point. When the relay coil is de-energized, spring pressure returns the movable contact point back against the fixed normally closed contact point. The resistor or diode is connected in parallel with the relay coil in the relay, and helps to dissipate voltage spikes and electromagnetic interference that can be generated as the electromagnetic field of the relay coil collapses.
The A/C clutch relay terminals are connected to the vehicle electrical system through a receptacle in the power distribution center (PDC). The inputs and outputs of the A/C clutch relay include
- The common feed terminal (30) receives a battery current input through a fused B(+) circuit at all times.
- The coil ground terminal (85) receives a ground input from the PCM through the A/C clutch relay control circuit only when the PCM electronically pulls the control circuit to ground.
- The coil battery terminal (86) receives a battery current input from fuse 18 (10 amp) in the PDC through a fused ignition switch output (run-start) circuit only when the ignition switch is in the On or Start positions.
- The normally open terminal (87) provides a battery current output to the A/C clutch coil through the A/C clutch relay output circuit only when the compressor clutch relay coil is energized.
- The normally closed terminal (87A) is not connected to any circuit in this application, but provides a battery current output only when the A/C clutch relay coil is de-energized.
The A/C clutch relay cannot be repaired and, if faulty or damaged, it must be replaced. Refer to SYSTEM WIRING DIAGRAMS for diagnosis and testing of the micro-relay and for complete HVAC wiring diagrams.
Scheme 292
- Disconnect and isolate the negative battery cable.
- Locate the power distribution center (PDC) (1).
- Open the PDC cover (2). NOTE: Refer to the fuse and relay layout map on the inner surface of the PDC cover for A/C clutch relay identification and location.
- Remove the A/C clutch relay (3) from the PDC.
A blower motor resistor block is used on vehicles equipped with the manual temperature control (MTC) heating-A/C system. Vehicles equipped with the automatic temperature control (ATC) heating-A/C system use a blower motor power module, instead of the blower motor resistor block (Refer to DESCRIPTION ).
The front blower motor resistor block is mounted to the rear of the HVAC housing, directly behind the glove box. The blower motor resistor block consists of a molded plastic mounting plate (1) with an integral wire connector receptacle (2). Concealed behind the mounting plate are coiled resistor wires contained within a ceramic heat sink (3). The front blower motor resistor block is accessed for service from beneath the right side of the instrument panel.
Scheme 293
The blower motor resistor block is connected to the vehicle electrical system through a dedicated wire lead and connector of the HVAC wire harness. The blower motor resistor block has multiple resistor wires, each of which will reduce the current flow through the blower motor to change the blower motor speed.
The blower motor switch in the MTC heating-A/C system directs the ground path for the blower motor through the correct resistor wire to obtain the selected speed. With the blower motor control in the lowest speed position, the ground path for the blower motor is applied through all of the resistor wires. Each higher speed selected with the blower motor control applies the blower motor ground path through fewer of the resistor wires, increasing the blower motor speed.
The blower motor resistor block cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
The ambient air temperature sensor is a variable resistor that monitors the air temperature outside of the vehicle. The ambient air temperature sensor is mounted onto the inside of front bumper beam and its data is used by the heating-A/C system to maintain optimum cabin temperature levels.
Scheme 294
The ambient air temperature sensor is a variable resistor that operates on a ground circuit and a 5-volt reference signal circuit sent by the front control module (FCM) through a two-wire lead and connector of the vehicle wire harness. The ambient air temperature sensor changes its internal resistance in response to changes in the outside air temperature, which either increases or decreases the reference signal voltage read by the FCM. The FCM converts and broadcasts the sensor data over the controller area network (CAN) B bus, where it is read by the A/C-heater control and other various vehicle control modules.
The ambient air temperature sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
The ambient air temperature sensor is diagnosed using the scan tool. Refer to ENGINE ELECTRICAL DIAGNOSTICS for more information.
Scheme 295
- Disconnect and isolate the negative battery cable.
- Remove the push pin (3) that secures the ambient air temperature sensor (1) to the inside of the front bumper beam.
- Disconnect the wire harness connector (2) from the ambient air temperature sensor and remove the sensor from the vehicle.
Scheme 296
- Connect the wire harness connector (2) to the ambient air temperature sensor (1).
- Position the ambient air temperature sensor to the inside of the front bumper beam.
- Install the push pin (3) that secures the ambient air temperature sensor to the front bumper beam.
- Reconnect the negative battery cable.
The evaporator temperature sensor is a two-wire temperature 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 evaporator temperature sensor grommet (2) seals the opening in the HVAC housing for the sensor wire lead and connector (3).
The external location of the evaporator temperature sensor allows the sensor to be removed or installed without disturbing the refrigerant in the A/C system.
Scheme 297
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 sensor will change its internal resistance in response to the temperatures it monitors 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 sensor decreases.
The A/C-heater control uses the resistance reading as an indication that conditions are correct to broadcast an A/C request message on the controller area network (CAN) B bus, where it is read by the front control module (FCM). The FCM then requests the powertrain control module (PCM) to cycle the A/C compressor clutch as necessary over the CAN C bus.
The evaporator temperature sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
The evaporator temperature sensor is diagnosed using a scan tool. Refer to HVAC - ELECTRICAL DIAGNOSTICS for more information.
Scheme 298
- Remove the HVAC housing (Refer to «HOUSING-HVAC»(ref-212853-S30259552272005122700000) ).
- Disconnect the HVAC wire harness (1) from the evaporator temperature sensor connector (2) located on the passenger side of the HVAC housing (3).
- Remove the evaporator temperature sensor wires (4) from the retainer (5) on the HVAC housing.
- Remove the grommet (6) from the opening in the HVAC housing.
- Carefully remove the probe of the evaporator temperature sensor from the fins of the A/C evaporator.
The infrared sensor consists of an infrared transducer (1) located on the driver side of the overhead console. The infrared sensor is used only on models equipped with the automatic temperature control (ATC) heater-A/C system. The infrared transducer is contained within a black molded plastic housing (2) with an integral wire connector receptacle (3). The integral mounting tab (4) allows the infrared sensor to be secured with one screw to the overhead console.
Scheme 299
The infrared sensor detects thermal radiation emitted by the driver seat occupant and its surroundings and converts its data into a linear pulse width modulated (PWM) output signal, which is sent to the compass temperature module ) (EOM) through a two-wire lead and connector of the vehicle wire harness. The EOM sends a message over the controller area network (CAN) B bus where it is read by the automatic temperature control (ATC) A/C-heater control. The ATC A/C-heater control uses the infrared sensor data as one of the inputs necessary to automatically control the interior cabin temperature level. By using thermal radiation (surface temperature) measurement, rather than an air temperature measurement, the ATC heating-A/C system is able to adjust itself to the comfort level as perceived by the occupant. This allows the ATC system to compensate for other ambient conditions affecting comfort levels, such as solar heat gain or evaporative heat loss.
The ATC system logic responds to the infrared sensor message from the EOM by calculating and adjusting the air flow temperature and air flow rate needed to properly obtain and maintain the selected comfort level temperature of the occupants. The EOM continually monitors the infrared sensor circuits, and will store a diagnostic trouble code (DTC) for any problem it detects.
The infrared sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
The infrared sensor is diagnosed using a scan tool. Refer to OVERHEAD CONSOLE - ELECTRICAL DIAGNOSTICS for more information.
Scheme 300
- Disconnect and isolate the negative battery cable.
- Remove the overhead console (2) and place it on a workbench (Refer to «OVERHEAD CONSOLE - SERVICE INFORMATION»(ref-212794-S10726649862005122700000) ).
- Remove the screw (3) that secures the infrared sensor (1) to the overhead console.
- Remove the infrared sensor from the overhead console.
Scheme 301
- Position the infrared sensor (1) onto the overhead console (2).
- Install the screw (3) that secures the infrared sensor to the overhead console. Tighten the screw to .2 N.m (17 in. lbs).
- Install the overhead console (Refer to «OVERHEAD CONSOLE - SERVICE INFORMATION»(ref-212794-S10726649862005122700000) ).
- Reconnect the negative battery cable.
The A/C pressure transducer (1) is a switch that is installed on a fitting located on the A/C discharge line. An internally threaded fitting on the A/C pressure transducer connects it to the externally threaded Schrader-type fitting on the A/C discharge line. A rubber O-ring seals the connection between the A/C pressure transducer and the discharge line fitting. The A/C pressure transducer is connected to the vehicle electrical system by a molded plastic connector with three terminals.
Scheme 302
The A/C pressure transducer monitors the pressures in the high side of the refrigerant system through its connection to a fitting on the discharge line. The A/C pressure transducer will change its internal resistance in response to the pressures it monitors. A Schrader-type valve in the discharge line fitting permits the A/C pressure transducer to be removed or installed without disturbing the refrigerant in the A/C system.
The front control module (FCM) provides a five volt reference signal to the A/C pressure transducer, then monitors the output voltage of the A/C pressure transducer on a sensor return circuit to determine refrigerant pressure. The FCM broadcasts a refrigerant pressure message to the PCM, which is programmed to respond to the A/C pressure transducer and other sensor inputs by controlling the operation of the A/C compressor clutch and the radiator cooling fan to help optimize A/C system performance and to protect the system components from damage. The PCM will disengage the A/C compressor clutch when high side pressure rises above 3172 kPa (460 psi) and re-engage the clutch when high side pressure drops below 1999 kPa (290 psi). The A/C pressure transducer will also disengage the A/C compressor clutch if the high side pressure drops below 193 kPa (28 psi) and will re-engage the clutch when the high side pressure rises above 234 kPa (34 psi). If the refrigerant pressure rises above 1655 kPa (240 psi), the PCM will actuate the cooling fan. The A/C pressure transducer message to the PCM will also prevent the A/C compressor clutch from engaging when ambient temperatures are below about 4.5°C (40°F) due to the pressure/temperature relationship of the refrigerant. Refer to the ELECTRIC A/C CONDENSER COOLING FAN SWITCH POINT CHART for condenser cooling fan on/off pressures.
The A/C pressure transducer cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
The A/C pressure transducer is diagnosed using a scan tool. Refer to ENGINE ELECTRICAL DIAGNOSTICS for more information.
See also:
• ENGINE ELECTRICAL DIAGNOSTICS