Part 2A

Fig.3 Blend Door Actuator:

REAR BLEND DOOR ACTUATOR
The blend door actuator is a reversible, 12-volt Direct Current (DC), servo motor. The single blend door actuator is located on the outboard side of the rear heater-A/C unit housing, below the mode door actuator. The blend door actuator is mechanically connected to the blend air door. The blend door actuator is interchangeable with the actuator for the mode door. Each actuator is contained within an identical black molded plastic housing with an integral wire connector receptacle. Two integral mounting tabs allow the actuator to be secured with two screws to the rear heater-A/C unit housing. Each actuator also has an identical output shaft with splines that connects it to the pivot or linkage of the proper door. The blend door actuator does not require mechanical indexing to the blend air door pivot, as it is electronically calibrated by the front heater-A/C control module. The blend door actuator cannot be adjusted or repaired and, if damaged or faulty it must be replaced.

The blend door actuator is connected to the front heater-A/C control module through the vehicle electrical system by a dedicated two-wire take out and connector of the rear HVAC wire harness. The blend door actuator can move the blend air door in two directions. When the front heater-A/C control module 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 module reverses the polarity of the voltage to the motor, the blend air door moves in the opposite direction. When the module makes the voltage to both connections high or both connections low, the blend air door stops and will not move. These same motor connections also provide a feedback signal to the front heater-A/C control module. This feedback signal allows the module to monitor the operation and relative positions of the blend door actuator and the blend air door. The front heater-A/C control module 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 circuits. A DTC can be retrieved and the blend door actuator can be diagnosed using a DRB III scan tool. Refer to the appropriate diagnostic information.

Fig.5 Blower Motor Relay:

REAR BLOWER MOTOR RELAY
The blower motor relay is a International Standards Organization (ISO) mini-relay. Relays conforming to the ISO specifications have common physical dimensions, current capacities, terminal patterns, and terminal functions. The ISO mini-relay terminal functions are the same as a conventional ISO relay. However, the ISO mini-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 blower motor relay is located in the Intelligent Power Module (IPM), which is in the engine compartment near the battery. See the fuse and relay layout map molded into the inner surface of the IPM cover for compressor clutch relay identification and location.

The black, molded plastic case is the most visible component of the blower motor 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 factory-installed blower motor relay cannot be adjusted or repaired. If the relay is damaged or faulty it must be replaced.

The blower motor relay is an electromechanical switch that uses a low current input from the Front Control Module (FCM) to control the high current output to the blower motor resistor (manual heater- A/C control) or blower power module (automatic heater-A/C control). 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 blower motor relay terminals are connected to the vehicle electrical system through a receptacle in the Intelligent Power Module (IPM). The inputs and outputs of the compressor clutch relay include:
- The common feed terminal (30) receives a battery current input from the battery through a B(+) circuit at all times.
- The coil ground terminal (85) receives a ground input through the front/rear blower motor relay control circuit only when the FCM electronically pulls the control circuit to ground.
- The coil battery terminal (86) receives a battery current input from the battery through a B(+) circuit at all times.
- The normally open terminal (87) provides a battery current output to the blower motor resistor (manual heater-A/C control) or blower power module (automatic heater-A/C control) through a fuse in the IPM on the fused rear blower motor relay output circuit only when the blower motor 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 blower motor relay coil is de-energized.

Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices, and grounds.

Fig.8 Blower Motor Resistor:

REAR BLOWER MOTOR RESISTOR
A blower motor resistor is used on this model when it is equipped with the manual heater-A/C control. Models equipped with the optional Automatic Temperature Control (ATC) use a blower power module, instead of the blower motor resistor. The blower motor resistor is installed in a mounting hole on the back of the rear heater-A/C unit housing, directly above the expansion valve. The resistor consists of a molded plastic mounting plate with an integral connector receptacle. Concealed behind the mounting plate within the rear heater-A/C unit housing are two coiled resistor wires contained within a protective stamped steel cage. The resistor mounting plate is secured with two screws to the rear heater- A/C unit housing and is accessed for service by removing the right quarter and D-pillar trim panels.

The blower motor resistor wires will get hot when in use. Do not touch the resistor wires or the protective cage if the blower motor has been running. The blower motor resistor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

The blower motor resistor is connected to the vehicle electrical system through a dedicated take out and connector of the rear HVAC wire harness. The blower motor resistor has two 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 manual heater-A/C control directs the ground path for the blower motor through the correct resistor wire to obtain the selected speed. With the blower motor switch in the lowest speed position, the ground path for the motor is applied through both resistor wires. Each higher speed selected with the blower motor switch applies the blower motor ground path through fewer of the resistor wires, increasing the blower motor speed. When the blower motor switch is in the highest speed position, the blower motor resistor wires are bypassed and the blower motor receives a direct path to ground through the blower motor switch. The blower motor resistor may be diagnosed using conventional diagnostic tools and methods.

REAR INFRARED TEMPERATURE SENSOR
The rear infrared temperature sensor consists of an infrared transducer that is concealed behind the lens of the rear heater-A/C control in the headliner. This sensor is used only on models equipped with the optional Automatic Temperature Control (ATC) heating and air conditioning system. The rear infrared temperature sensor is integral to the rear heater-A/C control. The infrared sensor cannot be adjusted or repaired and, if faulty or damaged, the rear heater- A/C control unit must be replaced.

The rear infrared temperature sensor provides an independent measurement input to the Automatic Temperature Control (ATC) heater-A/C control module that indicates the surface temperature of the rear seat occupants. By using a surface temperature measurement, rather than an air temperature measurement, the ATC system is able to adjust itself to the comfort level as perceived by the occupant. This allows the system to detect and 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 input by calculating and adjusting the air flow temperature and air flow rate needed to properly obtain and maintain the selected comfort level temperatures for the rear seat occupants. The ATC heater-A/C control module continually monitors the infrared sensor circuit, and will store a Diagnostic Trouble Code (DTC) for any problem it detects This DTC information can be retrieved and the infrared temperature sensor diagnosed using a DRB III scan tool Refer to the appropriate diagnostic information.

Fig.11 Power Module:

REAR POWER MODULE
A blower power module is used on this model when it is equipped with the optional Automatic Temperature Control (ATC). Models equipped with the standard manual heater-A/C control use a blower motor resistor, instead of the blower power module. The blower power module is installed in a mounting hole in the back of the rear heater-A/C unit housing, directly above the expansion valve. The module consists of a molded plastic mounting plate with two integral connector receptacles. Concealed behind the mounting plate within the evaporator housing is the power module electronic circuitry and a large finned, heat sink. The module mounting plate is secured with two screws to the rear heater-A/C unit housing and is accessed for service by removing the right quarter and D-pillar trim panels.

The power module heat sink will get hot when in use. Do not touch the heat sink if the blower motor has been running. The blower power module cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

The blower power module is connected to the vehicle electrical system through a dedicated take out and connector of the rear HVAC wire harness. A second connector receptacle receives the pigtail wire connector from the blower motor. The blower power module allows the microprocessor-based Automatic Temperature Control (ATC) heater-A/C control module 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 adjusts the voltage output received from the blower motor relay to change or maintain the desired blower speed. The blower power module is diagnosed using a DRB III scan tool. Refer to the appropriate diagnostic information.

Fig.1 Air Filter:

AIR FILTER
A dust and odor air filter is standard equipment on models equipped with the dual zone or three zone temperature control systems. The filter element is the same size as the front air conditioner evaporator to ensure ample filtering capacity. A removable door on the bottom of the front heater-A/C unit housing below the glove box provides easy access to the filter element for replacement. Filter replacement is recommended at 24,000 kilometer (15,000 mile) intervals.

FRONT AIR OUTLETS
Based upon the system mode selected, conditioned air can exit the front heater-A/C unit housing through one or a combination of the four main housing outlets: defrost, demist, panel, or floor. Once the conditioned air exits the unit housing, it is directed through molded plastic ducts to the various outlets in the vehicle interior. These outlets and their locations are as follows:
- Defroster Outlet - A single, centrally mounted outlet delivers air for defrosting the large windshield. Because outlet vanes are not needed to direct flow, a simple, integral grid is molded into the center of the instrument panel top cover to prevent objects from falling into the duct. If the defroster outlet is faulty or damaged, the instrument panel top cover must be replaced.
- Demister Outlets - There are two side window demisters that aid in defogging and defrosting the front door windows. One demister outlet is located at each outboard end of the instrument panel top pad, near the belt line at the A-pillars. The demister outlets can be removed from the top pad individually for service replacement.
- Instrument Panel Outlets - There are five panel outlets in the instrument panel, one located near each outboard end of the instrument panel facing the rear of the vehicle, and three located near the top of the instrument panel center bezel. On models with manual temperature control, all five of these outlets are fully adjustable. On models with Automatic Temperature Control (ATC), the center outlet in the center bezel has fixed vanes because it also houses the remote infrared temperature sensors for the front seat positions. The outboard outlets can be removed individually for service replacement. The center bezel outlets are serviced as a gang of three outlets and, on models with ATC, also includes the infrared sensors.
- Front Door Rear Outlets - A fully adjustable outlet located at the rear of each front door trim panel supplies only cooled air to the intermediate seat passengers. Air is supplied to these outlets from the instrument panel through ducts in the doors that use molded seals at the instrument panel to prevent air leakage. The door ducts are integral to the front door trim panels. These outlets also incorporate a red reflector to improve the safety and visibility of an opened front door to traffic approaching the vehicle from the rear at night. These outlets can be removed from the door trim panels for service replacement.
- Front Floor Outlets - There are two front floor outlets, one located above each side of the floor panel center tunnel below the instrument panel. These outlets are integral to the front heater-A/C unit distribution housing.
- Rear Floor Outlets - Wide rear floor outlets located under each front seat have integral, fixed directional dividers to distribute heated air across the floor for intermediate seat passengers. These outlets are integral to the floor distribution ducts routed under the front floor carpet from an outlet nozzle on the bottom of the front heater-A/C unit distribution housing.

Fig.7 Blower Motor:

FRONT BLOWER MOTOR
The blower motor is a 12-volt, Direct Current (DC) motor with a squirrel cage-type blower wheel that is secured to the blower motor shaft. The blower motor and wheel are located near the passenger side end of the heater-A/C unit within the two halves of the intake air housing in the passenger compartment below the instrument panel. The blower motor and blower motor wheel are a factory balanced unit and cannot be adjusted or repaired. If faulty or damaged, the blower motor and blower wheel must be replaced as a unit.

The blower motor will operate whenever the ignition switch is in the ON position and the heater-A/C control power is turned on. The blower motor can only be turned OFF by turning OFF the power at the heater-A/C control. The blower motor receives battery current whenever the front blower motor relay is energized. The front blower motor relay output circuit is protected by a fuse in the Intelligent Power Module (IPM) located in the engine compartment near the battery In the Manual system, the blower motor speed is controlled by regulating the path to ground through the blower control switch and the blower motor resistor. In the ATC system, the blower motor speed is controlled by an electronic blower power module, which uses a pulse width modulated input from the ATC module and feedback from the blower motor to regulate the blower motor ground path it provides. The blower motor and wheel are used to control the velocity of air moving through the heater-A/C unit housing. The blower motor controls the velocity of the air flowing through the heater-A/C housing by spinning the blower wheel within the housing at the selected speed or, in the ATC system, at the selected or programmed speed.