Part 1B

Fig.17 Compressor Clutch Relay:

COMPRESSOR CLUTCH RELAY
The compressor 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 compressor clutch 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 compressor 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 compressor 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 compressor clutch electromagnetic 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 compressor clutch 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 a fuse in the IPM through a fused B(+) circuit at all times.
- The coil ground terminal (85) receives a ground input from the PCM through the compressor 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 the PCM 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 compressor clutch coil through the compressor 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 compressor clutch 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.18 Evaporator Temperature Sensor:

EVAPORATOR TEMPERATURE SENSOR
The evaporator temperature sensor is a switch that is installed on the top of the expansion valve in the right rear corner of the engine compartment. The sensor has a small probe that is inserted in a small well in the body of the expansion valve that is filled with a special silicone-based thermal grease. A small molded plastic push-in retainer secures the sensor to a threaded hole in the top surface of the expansion valve. Two terminals within a molded plastic connector receptacle on the sensor connect it to the vehicle electrical system through a take out and connector of the HVAC wire harness.

The evaporator temperature sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

The evaporator temperature sensor monitors the temperature of the evaporator through its connection to the top of the expansion valve. The sensor will change its internal resistance in response to the temperatures it monitors. The heater-A/C control module is connected to the sensor through a sensor ground circuit and a sensor signal circuit. As the evaporator temperature increases, the resistance of the sensor decreases and the voltage monitored by the module decreases. The module uses this monitored voltage reading to an indication of the evaporator temperature. The heater-A/C control module is programmed to respond to this input by sending electronic messages to the Powertrain Control Module (PCM) over the Programmable Communications Interface (PCI) data bus, and the PCM then cycles the air conditioning compressor clutch as necessary to optimize air conditioning system performance and to protect the system from evaporator freezing. The external location of the sensor and the use of a screw allows the sensor to be removed or installed from the expansion valve without disturbing the refrigerant in the system. The evaporator temperature sensor is diagnosed using a DRB III scan tool. Refer to the appropriate diagnostic information.

Fig.19 Infrared Temperature Sensor:

FRONT INFRARED TEMPERATURE SENSOR
The infrared temperature sensor consists of two infrared transducers that are concealed behind a clear lens located near the bottom of the center panel outlet near the top of the instrument panel center bezel. These sensors are used only on models equipped with the optional Automatic Temperature Control (ATC) heating and air conditioning system. A molded plastic connector receptacle on the bottom of the panel outlet unit is concealed behind the center bezel. A short, dedicated jumper wire harness routed behind the center bezel connects the sensors directly to the ATC heater-A/C control module near the bottom of the center bezel. The infrared temperature sensor is integral to the center bezel panel outlet unit. The infrared sensors cannot be adjusted or repaired and, if faulty or damaged, the center bezel panel outlet unit must be replaced.

The dual infrared temperature sensors provide independent measurement inputs to the Automatic Temperature Control (ATC) heater-A/C control module that indicates the surface temperature of the driver seat and front seat passenger 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 inputs by calculating and adjusting the air flow temperature and air flow rate needed to properly obtain and maintain the individually selected comfort level temperatures of both the driver and passenger seat occupants. The ATC heater-A/C control module continually monitors the infrared sensor circuits, 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.20 Mode Door Actuator:

MODE DOOR ACTUATOR
The mode door actuator is a reversible, 12-volt Direct Current (DC), servo motor. The single mode door actuator is located on the driver side end of the heater-A/C housing unit, close to the top of the distribution housing. The mode door actuator is mechanically connected to the mode door. The mode door actuator is interchangeable with the actuators for the blend air door(s) and the recirculation air 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 heater-A/C unit housing. Each actuator also has an identical output shaft with splines that connects it to the linkage that drives the mode door. The mode door actuator does not require mechanical indexing to the mode door linkage, as it is electronically calibrated by the heater-A/C control module. The mode door actuator cannot be adjusted or repaired and, if damaged or faulty, it must be replaced.

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

Fig.22 Power Module:

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 evaporator housing, directly behind the glove box opening of the instrument panel. 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 evaporator housing and is accessed for service by rolling down the glove box from the instrument panel.

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 instrument panel 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.23 Recirculation Door Actuator:

RECIRCULATION DOOR ACTUATOR
The recirculation door actuator is a reversible, 12-volt Direct Current (DC), servo motor. The single recirculation door actuator is located on the passenger side end of the heater-A/C housing unit, on the bottom of the lower intake air housing. The recirculation door actuator is mechanically connected to the recirculation air door. The recirculation door actuator is interchangeable with the actuators for the blend air door(s) and 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 lower intake air housing. Each actuator also has an identical output shaft with splines that connects it to the linkage that drives 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 heater-A/C control module. The recirculation door actuator cannot be adjusted or repaired and, if damaged or faulty it must be replaced.

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