Part 1 of 2

BLEND-AIR DOOR MOTOR
The blend-air door on heater-only and heater-A/C models is connected with a short mechanical link to an electronic blend-air door actuator motor. The blend-air door motor controls the positioning of the blend-air door in the heater-A/C housing. The blend- air door motor is mounted to the top of the right end of the distribution duct under the instrument panel in the passenger compartment.

A mechanical link is attached to the end of the blend-air door motor lever in the passenger compartment and passes through a bellows-type boot and a small hole in the dash panel to the engine compartment. In the engine compartment, the link is attached to the end of the blend air door lever on the top cover of the heater-A/C housing.

The blend-air door motor is controlled by a potentiometer that is integral to the heater-only or heater-A/C control. The rotary-type temperature control knob positions the potentiometer, and the potentiometer controls the voltage to the blend-air door motor. The blend-air door motor moves the blend-air door based upon the voltage level of the signal received from the potentiometer.

The blend-air door motor is accessible for service through the instrument panel glove box opening. The blend-air door motor cannot be repaired and, if faulty or damaged, it must be replaced. The mechanical link and boot are available for service replacement.

BLOWER MOTOR
Front
The front blower motor and blower wheel are located in the blower housing in the engine compartment. The blower housing is integral to the recirculation housing, which is secured to the dash panel and the right cowl side inner panel below the heater-A/C housing. The blower motor controls the volume of air flowing through the heater-A/C system by spinning a squirrel cage-type blower wheel within the housing at the selected speed. The blower motor and blower wheel can be accessed for service from the engine compartment.

The front blower motor will only operate when the ignition switch is in the ON position, and when the heater-only or heater-A/C mode control switch knob is in any position, except OFF. The blower motor receives a fused battery feed through the blower motor relay whenever the ignition switch is in the ON position. The blower motor battery feed circuit is protected by a fuse in the Power Distribution Center (PDC). The blower motor relay control circuit is protected by a fuse in the junction block.

Blower speed is controlled by regulating the blower motor ground path through the heater-A/C mode control switch, the front blower motor switch, the blower motor resistor, and the high speed blower motor relay. When the blower motor switch is placed in the highest speed position it energizes the high speed blower motor relay, which then provides a direct ground feed to the blower motor and bypasses the remainder of the blower motor resistors.

The blower motor and blower motor wheel cannot be repaired and, if faulty or damaged, they must be replaced. The blower motor and blower wheel are each serviced separately.

Rear
The rear blower motor and blower wheel are located in the optional rear heater-A/C unit housing in the passenger compartment. The rear heater-A/C unit is secured to the floor panel between the fuel filler inlet housing and the left rear wheel house against the left side panel. The blower motor controls the velocity of air flowing through the rear heater A/C system by spinning a squirrel cage-type blower wheel within the housing at the selected speed. The blower motor and blower wheel can be accessed for service from the passenger compartment.

The rear blower motor will only operate when the ignition switch is in the ON position. The blower motor receives a fused battery feed through the ignition run relay whenever the ignition switch is in the ON position. The blower motor battery feed circuit is protected by a fuse in the Power Distribution Center (PDC). The blower motor relay control circuit is protected by a fuse in the junction block.

Blower speed is controlled by regulating the blower motor ground path through the blower motor switch, the blower motor resistor, and the high speed blower motor relay. When the rear blower motor switch is placed in the highest speed position it energizes the high speed blower motor relay, which then provides a direct ground feed to the blower motor and bypasses the blower motor resistors.

The rear blower motor and blower motor wheel cannot be repaired and, if faulty or damaged, they must be replaced. The blower motor and blower wheel are each serviced separately.

BLOWER MOTOR RELAY
Front
The front blower motor relay is a International Standards Organization (ISO)-type relay. The relay is an electromechanical device that switches battery current from a fuse in the Power Distribution Center (PDC) directly to the blower motor. The relay is energized when the relay coil is provided a ground signal by the blower switch. This arrangement reduces the amount of battery current that must flow through the ignition switch.

The blower motor relay control circuit is protected by a fuse located in the fuse block. When the relay is de-energized, the blower motor ground path through the high blower relay is interrupted.

The front blower motor relay is located in the PDC in the engine compartment. Refer to the PDC label for blower motor relay identification and location.

The blower motor relay cannot be repaired and, if faulty or damaged, it must be replaced.

Rear
The blower motor relay for the optional rear heater-A/C unit is a International Standards Organization (ISO)-type relay. The relay is energized when the relay coil is provided a ground signal by the blower switch. This arrangement reduces the amount of battery current that must flow through the blower switch.

The blower motor relay control circuit is protected by a fuse located in the junction block. When the relay is de-energized, the blower motor ground path through the high blower relay is interrupted.

The rear blower motor relay is located in a connector that is secured to the back of the rear heater-A/C unit housing in the passenger compartment.

The blower motor relay cannot be repaired and, if faulty or damaged, it must be replaced.

BLOWER MOTOR RESISTOR
Front
The front blower motor resistor is mounted to the inboard side of the heater-A/C housing in the engine compartment. It can be accessed for service from the engine compartment. It is secured to the housing with two screws and is connected to the headlamp and dash wire harness.

The blower motor resistor has multiple resistor wires, each of which will change the resistance in the blower motor ground path to change the blower motor speed. The blower motor switch directs the ground path through the correct resistor wire to obtain the selected blower motor speed.

With the blower motor switch in the lowest speed position the ground path for the motor is applied through all of the 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 is bypassed and the blower motor receives a direct path to ground through the high speed blower motor relay.

The front blower motor resistor cannot be repaired and, if faulty or damaged, it must be replaced.

Rear
The optional rear heater-A/C unit has a blower motor resistor mounted to the inside of the unit lower housing in the passenger compartment. It can be accessed for service through the horizontal duct opening in the rear heater-A/C unit upper housing. It is secured to the inside of the lower housing by two mounting tabs and a snap feature that are molded into the lower housing, and it is connected to the rear heater-A/C unit wire harness.

The blower motor resistor has multiple resistor wires, each of which will change the resistance in the blower motor ground path to change the blower motor speed. The blower motor switch directs the ground path through the correct resistor wire to obtain the selected blower motor speed.

With the blower motor switch in the lowest speed position the ground path for the motor is applied through all of the 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 is bypassed and the blower motor receives a direct path to ground through the high speed blower motor relay.

The rear blower motor resistor cannot be repaired and, if faulty or damaged, it must be replaced.

BLOWER MOTOR SWITCH
Front
The front blower motor is controlled by a four position rotary-type blower motor switch, mounted in the heater-only or heater-A/C control panel. The switch allows the selection of one of four blower motor speeds, but can only be turned off by selecting the OFF position with the heater-A/C mode control switch knob.

The blower motor switch directs the blower motor ground path from the mode control switch to the blower motor resistor, or provides a ground directly to the high speed blower motor relay, as required to achieve the selected blower motor speed.

The front blower motor switch cannot be repaired and, if faulty or damaged, the entire heater-only or heater-A/C control unit must be replaced. The blower motor switch knob is serviced separately.

Rear
The optional rear heater-A/C unit blower motor is controlled by a four position rotary-type blower motor switch, mounted in the accessory switch plate located to the right of the heater-A/C control on the instrument panel. The switch allows the selection of one of three blower motor speeds and an OFF position.

The rear blower motor switch directs the blower motor ground path to the blower motor resistor, or provides a ground directly to the high speed blower motor relay, as required to achieve the selected blower motor speed.

The rear blower motor switch cannot be repaired and, if faulty or damaged, it must be replaced. The rear blower motor switch knob is serviced separately The rear blower motor switch also has a replaceable incandescent-type illumination lamp bulb.

COMBINATION COIL
Models equipped with the optional rear heater-A/C unit have a combination coil located within the rear unit housing. It is called a combination coil because it combines the functions of a heater core and an evaporator coil into a single heat exchanger unit.

The combination coil features six rows of tube and fin construction. The two rows located toward the outboard side of the vehicle serve as the heater core and have engine coolant circulated through them whenever the rear water valve is open. The four rows toward the inboard side of the vehicle serve as the evaporator and have refrigerant circulated through them whenever the air conditioning compressor is operating. The amount of refrigerant flowing through the combination coil is controlled by a dedicated rear thermal expansion valve.

The combination coil can be accessed for service by removing the rear heater-A/C unit upper housing The combination coil cannot be repaired and, if faulty or damaged, it must be replaced.

COMPRESSOR

Sanden TRS-105 Scroll-Type Compressor:

The air conditioning system uses a Sanden TRS-105 fixed displacement scroll-type compressor on all models. This compressor uses an integral thermal limiter switch to protect it from overheating. A label identifying the use of R-134a refrigerant is located on the compressor.

The compressor is driven by the engine through an electric clutch, drive pulley and belt arrangement. The compressor is lubricated by refrigerant oil that is circulated throughout the refrigerant system with the refrigerant.

The compressor draws in low-pressure refrigerant vapor from the evaporator through its suction port. It then compresses the refrigerant into a high-pressure, high-temperature refrigerant vapor, which is then pumped to the condenser through the compressor discharge port.

The compressor cannot be repaired. If faulty or damaged, the entire compressor must be replaced. The thermal limiter switch is only available as a part of a replacement compressor assembly. The compressor clutch, pulley, and clutch coil, are available for service.

COMPRESSOR CLUTCH

Compressor Clutch - Typical:

The compressor clutch assembly consists of a stationary electromagnetic coil, a hub bearing and pulley assembly, and a clutch plate. The electromagnetic coil unit and the hub bearing and pulley assembly are each retained on the nose of the compressor front housing with snap rings. The clutch plate is mounted on the compressor shaft and secured with a nut.

These components provide the means to engage and disengage the compressor from the engine serpentine accessory drive belt. When the clutch coil is energized, it magnetically draws the clutch plate into contact with the 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 compressor clutch and coil are the only serviced parts on the compressor.

The compressor clutch is controlled by several components: the heater-A/C mode control switch, the low pressure cut-off switch, the high pressure cut-off switch, the fin sensing cycling clutch switch, the thermal limiter switch, the compressor clutch relay, and the Powertrain Control Module (PCM). The PCM may delay compressor clutch engagement for up to 30 seconds. Refer to Fuel System for more information on the PCM controls.

COMPRESSOR CLUTCH RELAY
The compressor clutch relay is a International Standards Organization (ISO) micro-relay. The terminal designations and functions are the same as a conventional ISO relay. However, the micro-relay terminal orientation (footprint) is different, the current capacity is lower, and the relay case dimensions are smaller than those of the conventional ISO relay.

The compressor clutch relay is an electromechanical device that switches battery current to the compressor clutch coil when the Powertrain Control Module (PCM) grounds the coil side of the relay. The PCM responds to inputs from the heater-A/C mode control switch, the low pressure cut-off switch, the high pressure cut-off switch, and the fin sensing cycling clutch switch.

The compressor clutch relay is located in the Power Distribution Center (PDC) in the engine compartment. Refer to the PDC label for relay identification and location.

The compressor clutch relay cannot be repaired and, if faulty or damaged, it must be replaced.

CONDENSER
The condenser is located in the air flow in front of the engine cooling radiator. The condenser is a heat exchanger that allows the high-pressure refrigerant gas being discharged by the compressor to give up its heat to the air passing over the condenser fins.

When the refrigerant gas gives up its heat, it condenses. When the refrigerant leaves the condenser, it has become a high-pressure liquid refrigerant. The volume of air flowing over the condenser fins is critical to the proper cooling performance of the air conditioning system. Therefore, it is important that there are no objects placed in front of the radiator grille openings in the front of the vehicle or foreign material on the condenser fins that might obstruct proper air flow. Also, any factory-installed air seals or shrouds must be properly reinstalled following radiator or condenser service.

The condenser cannot be repaired and, if faulty or damaged, it must be replaced.

EVAPORATOR COIL
Front
The evaporator coil is located in the heater-A/C housing, on the right side of the engine compartment. The evaporator coil is positioned in the heater-A/C housing so that all air that enters the housing must pass over the fins of the evaporator before it is distributed through the system ducts and outlets. However, air passing over the evaporator coil fins will only be conditioned when the compressor is engaged and circulating refrigerant through the evaporator coil tubes.

Refrigerant enters the evaporator from the expansion valve as a low-temperature, low-pressure mixture of liquid and gas. As air flows over the fins of the evaporator, the humidity in the air condenses on the fins, and the heat from the air is absorbed by the refrigerant. Heat absorption causes the refrigerant to boil and vaporize. The refrigerant becomes a low- pressure gas before it leaves the evaporator.

The evaporator coil cannot be repaired and, if faulty or damaged, it must be replaced.

Rear
Models equipped with the optional rear heater-A/C unit have a combination coil located within the rear unit housing.

The combination coil functions as both the rear heater core and the rear evaporator coil.

EXPANSION VALVE
Front
The front "H" valve-type thermal expansion valve (TXV) is located at the front of the heater-A/C housing between the liquid and suction lines and the evaporator coil. High-pressure, high temperature liquid refrigerant from the liquid line passes through the expansion valve orifice, converting it into a low-pressure, low-temperature mixture of liquid and gas before it enters the evaporator coil.

A temperature sensor in the expansion valve control head monitors the temperature of the refrigerant leaving the evaporator coil through the suction line, and adjusts the orifice size at the liquid line to let the proper amount of refrigerant into the evaporator coil to meet the vehicle cooling requirements. Controlling the refrigerant flow through the evaporator ensures that none of the refrigerant leaving the evaporator is still in a liquid state, which could damage the compressor.

The expansion valve is a factory calibrated unit and cannot be adjusted or repaired. If faulty or damaged, the expansion valve must be replaced.

Rear
Models equipped with the optional rear heater-A/C unit have a second "H" valve-type thermal expansion valve (TXV) installed between the rear unit liquid and suction lines, and the combination coil. High- pressure, high temperature liquid refrigerant from the liquid line passes through the expansion valve orifice, converting it into a low-pressure, low-temperature mixture of liquid and gas before it enters the combination coil.

A temperature sensor in the expansion valve control head monitors the temperature of the refrigerant leaving the combination coil through the suction line, and adjusts the orifice size at the liquid line to let the proper amount of refrigerant into the combination coil to meet the vehicle cooling requirements. Controlling the refrigerant flow through the combination coil ensures that none of the refrigerant leaving the combination coil is still in a liquid state, which could damage the compressor.

The rear expansion valve is a factory calibrated unit and cannot be adjusted or repaired. If faulty or damaged, the expansion valve must be replaced.