Automatic HVAC Systems - Controls - Front Dodge Grand Caravan IV

STANDARD PROCEDURE - HEATER-A/C CONTROL CALIBRATION

The heater-A/C control module must be recalibrated each time an actuator motor or the control module is replaced. If the vehicle is so equipped, the calibration procedure also includes rear HVAC positions for each actuator motor.

1. Turn the ignition switch to the On position.
2. Simultaneously depress and hold the Power and Recirculation buttons on the heater-A/C control for at least five seconds. The manual heater-A/C control power Light Emitting Diode (LED) and Recirculation LED, or the Automatic Temperature Control (ATC) heater-A/C control Delay and Recirculation graphics will begin to flash when the calibration procedure has begun.
3. The calibration procedure should take less than two minutes to complete for the manual heater-A/C control, and less than twenty seconds for the ATC heater-A/C control. When the LEDs or graphics stop flashing, the calibration procedure is complete.
4. If the LEDs or graphics continue to flash beyond the normal three minute (manual) or twenty second (ATC) calibration time, it indicates that the heater-A/C control has detected a failure and a Diagnostic Trouble Code (DTC) has been set. Use a DRBIII(R) scan tool to perform further diagnosis. Refer to the appropriate diagnostic information. The LEDs or graphics will continue to flash even after the ignition switch is cycled Off and On, until a successful calibration is completed or until the vehicle has been driven about 13 kilometers (8 miles).

REMOVAL

Scheme 23

1. Disconnect and isolate the battery negative cable.
2. Remove the center bezel from the instrument panel. (Refer to INSTRUMENT PANEL CENTER BEZEL - REMOVAL ).
3. Place the instrument panel center bezel unit face down on a suitable work surface. Take the proper precautions to protect the center bezel from cosmetic damage.
4. If the vehicle is equipped with the optional Automatic Temperature Control (ATC) system, disconnect the infrared sensor jumper harness connector from the receptacle on the back of the heater-A/C control (Scheme 23)
5. Remove the six screws that secure the heater-A/C control to the back of the instrument panel center bezel.
6. Remove the heater-A/C control from the instrument panel center bezel.

INSTALLATION

1. Position the heater-A/C control onto the back of instrument panel center bezel.
2. Install and tighten the six screws that secure the heater-A/C control to the back of the instrument panel center bezel. Tighten the screws to 2 N.m (17 in. lbs.).
3. If the vehicle is equipped with the optional ATC system, reconnect the infrared sensor jumper harness connector to the receptacle on the back of the heater-A/C control.
4. Reinstall the center bezel onto the instrument panel. (Refer to INSTRUMENT PANEL CENTER BEZEL - INSTALLATION ).
5. Reconnect the battery negative cable.

DESCRIPTION - A/C PRESSURE TRANSDUCER

The A/C pressure transducer (Scheme 24) is a switch that is installed on a fitting located on the refrigerant liquid line between the filter-drier and the expansion valve in the right rear corner of the engine compartment. An internally threaded hex fitting on the transducer connects it to the externally threaded Schrader-type fitting on the liquid line. A rubber O-ring seals the connection between the transducer and the liquid line fitting. Three terminals within a molded plastic connector receptacle on the top of the transducer connect it to the vehicle electrical system through a take out and connector of the headlamp and dash wire harness.

Scheme 24

The A/C pressure transducer cannot be adjusted or repaired and, if faulty or damaged, it musty be replaced.

OPERATION

The A/C pressure transducer monitors the pressures in the high side of the refrigerant system through its connection to a fitting on the liquid line. The transducer will change its internal resistance in response to the pressures it monitors. The Powertrain Control Module (PCM) provides a five volt reference signal and a sensor ground to the transducer, then monitors the output voltage of the transducer on a sensor return circuit to determine refrigerant pressure. The PCM is programmed to respond to this and other sensor inputs by controlling the operation of the air conditioning compressor clutch and the radiator cooling fan to help optimize air conditioning system performance and to protect the system components from damage. The A/C pressure transducer input to the PCM will also prevent the air conditioning compressor clutch from engaging when ambient temperatures are below about 10° C (50° F) due to the pressure/temperature relationship of the refrigerant. The Schrader-type valve in the liquid line fitting permits the A/C pressure transducer to be removed or installed without disturbing the refrigerant in the system. The A/C pressure transducer is diagnosed using a DRBIII(R) scan tool. Refer to the appropriate diagnostic information.

DIAGNOSIS AND TESTING - A/C PRESSURE TRANSDUCER

The A/C pressure transducer is tested using a DRBIII(R) scan tool. Refer to the appropriate diagnostic information. Before testing the A/C pressure transducer, be certain that the transducer wire harness connection is clean of corrosion and properly connected. For the air conditioning system to operate, an A/C pressure transducer voltage reading between 0.451 and 4.519 volts is required. Voltages outside this range indicate a low or high refrigerant system pressure condition to the Powertrain Control Module (PCM). The PCM is programmed to respond to a low or high refrigerant system pressure by suppressing operation of the compressor. Refer to the A/C Pressure Transducer Voltage table for the possible condition indicated by the transducer voltage readings.

Scheme 25

Scheme 26

1. Disconnect and isolate the battery negative cable.
2. Disconnect the headlamp and dash wire harness connector for the A/C pressure transducer from the transducer connector receptacle (Scheme 26)
3. Using an open end wrench, unscrew the A/C pressure transducer from the fitting on the liquid line between the filter-drier and the expansion valve.
4. Remove the seal from the A/C pressure transducer fitting and discard.

1. Lubricate a new rubber O-ring seal with clean refrigerant oil and install it on the A/C pressure transducer fitting.
2. Using an open end wrench, install and tighten the A/C pressure transducer onto the fitting on the liquid line between the filter-drier and the expansion valve.
3. Reconnect the headlamp and dash wire harness connector for the A/C pressure transducer to the transducer connector receptacle.
4. Reconnect the battery negative cable.

DESCRIPTION

The blend door actuators are reversible, 12-volt Direct Current (DC), servo motors. Models with the single zone heater and air conditioner system have a single blend air door, which is controlled by a single blend door actuator. Models with the optional dual zone front heater and air conditioner system have dual blend air doors, which are controlled by two blend door actuators. The single zone blend door actuator is located on the driver side end of the heater-A/C housing unit, close to the dash panel. In the dual zone system, the same blend door actuator used for the single zone system becomes the passenger blend door actuator, and is mechanically connected to only the passenger side blend air door. In the dual zone system, a second separate blend door actuator is also located on the driver side end of the heater-A/C housing unit close to the instrument panel, and is mechanically connected to only the driver side blend air door.

The blend door actuators are interchangeable with each other, as well as with the actuators for the mode door 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 proper blend air door. The blend door actuators do not require mechanical indexing to the blend door linkage, as they are electronically calibrated by the heater-A/C control module. The blend door actuators cannot be adjusted or repaired and, if damaged or faulty, they must be replaced.

Each blend 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 blend door actuator can move the blend air 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 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 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 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. The blend door actuator can be diagnosed using a DRBIII(R) scan tool. Refer to the appropriate diagnostic information.

The single zone heating and air conditioning system is equipped with a single blend door actuator. The dual zone system has two blend door actuators, one for the driver side blend air door and one for the passenger side blend air door. The same service procedures can be used for each of these actuators.

Scheme 27

Scheme 28

1. Disconnect and isolate the battery negative cable.
2. Remove the silencer from beneath the driver side end of the instrument panel. (Refer to INSTRUMENT PANEL SILENCER - REMOVAL ).
3. Remove the three screws that secure the heater core shield to the left end of the HVAC distribution housing (Scheme 27)
4. Pull the heater core shield rearward far enough to disengage the two location tabs that position the front of the shield to the receptacles in the two lower finger formations of the heater/air conditioner housing near the dash panel.
5. Remove the heater core shield from the distribution housing.
6. Disconnect the HVAC wire harness connector for the blend door actuator from the actuator connector receptacle (Scheme 28)
7. Remove the two screws that secure the blend door actuator to the distribution housing.
8. Remove the blend door actuator from the distribution housing.

1. Position the blend door actuator onto the heater/air conditioner housing. If necessary, rotate the actuator slightly to align the splines on the actuator output shaft with those in the blend air door linkage.
2. Install and tighten the two screws that secure the blend door actuator to the distribution housing. Tighten the screws to 2 N.m (17 in. lbs.).
3. Reconnect the HVAC wire harness connector for the blend door actuator to the actuator connector receptacle.
4. Position the heater core shield onto the distribution housing. Be certain that the two location tabs on the front of the shield are engaged in the receptacles in the two lower finger formations of the evaporator housing near the dash panel.
5. Install and tighten the three screws that secure the heater core shield to the left end of the heater/air conditioner housing. Tighten the screws to 2 N.m (17 in. lbs.).
6. Reinstall the silencer under the driver side end of the instrument panel. (Refer to INSTRUMENT PANEL SILENCER - INSTALLATION ).
7. Reconnect the battery negative cable.
8. Perform the heater-A/C control calibration procedure. (Refer to «STANDARD PROCEDURE - HEATER-A/C CONTROL CALIBRATION»(/dodge/grand-caravan/iv-2000-2007/remont/automatic-hvac-system/#automatic-hvac-systems-controls-front__standard-procedure-heater-ac-control-calibration) ).

The blower motor relay (Scheme 29) 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 blower motor relay identification and location.

Scheme 29

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 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 (ATC 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 blower motor relay include

1. The common feed terminal (30) receives a battery current input from the battery through a B(+) circuit at all times.
2. 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.
3. The coil battery terminal (86) receives a battery current input from the battery through a B(+) circuit at all times.
4. 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 front blower motor relay output circuit only when the blower motor relay coil is energized.
5. 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.

DIAGNOSIS AND TESTING - BLOWER MOTOR RELAY

The front blower motor relay (Scheme 30) 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 front blower motor relay identification and location. Remove the relay from the IPM to perform the following tests

Scheme 30

1. A relay in the de-energized position should have continuity between terminals 87A and 30, and no continuity between terminals 87 and 30. If OK, go to Step 2. If not OK, replace the faulty relay.
2. Resistance between terminals 85 and 86 (electromagnet) should be 75 + 5 ohms. If OK, go to Step 3. If not OK, replace the faulty relay.
3. Connect a battery to terminals 85 and 86. There should now be continuity between terminals 30 and 87, and no continuity between terminals 87A and 30. If OK, use a DRBIII(R) scan tool to perform further diagnosis of the relay circuits. Refer to the appropriate diagnostic information. If not OK, replace the faulty relay.

Scheme 31

1. Disconnect and isolate the battery negative cable.
2. Unlatch and remove the cover from the Intelligent Power Module (IPM) (Scheme 31)
3. See the fuse and relay layout map molded into the inner surface of the IPM cover for front blower motor relay identification and location.
4. Remove the front blower motor relay from the IPM by pulling the relay straight up.

1. See the fuse and relay layout map molded into the inner surface of the Intelligent Power Module (IPM) cover for front blower motor relay identification and location.
2. Position the front blower motor relay to the proper receptacle in the IPM.
3. Align the front blower motor relay terminals with the terminal cavities in the IPM relay receptacle.
4. Push down firmly on the front blower motor relay until the terminals are fully seated in the terminal cavities in the IPM receptacle.
5. Install and latch the cover onto the IPM.
6. Reconnect the battery negative cable.

A blower motor resistor is used on this model when it is equipped with the manual heater-A/C control (Scheme 32) 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 in the heater/AC housing, directly behind the glove box opening of the instrument panel. The resistor consists of a molded plastic mounting plate with two integral connector receptacles. Concealed behind the mounting plate within the heater/AC housing are four coiled resistor wires contained within a protective stamped steel cage. The resistor mounting plate is secured with two screws to the heater/AC housing and is accessed for service by rolling down the glove box from the instrument panel.

Scheme 32

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 instrument panel wire harness. A second connector receptacle receives the pigtail wire connector from the blower motor. The blower motor resistor 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 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 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 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.

DIAGNOSIS AND TESTING - BLOWER MOTOR RESISTOR

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

1. Disconnect and isolate the battery negative cable.
2. Disconnect the instrument panel wire harness connector for the blower motor resistor and the blower motor pigtail wire connector from the resistor connector receptacles.
3. Check for continuity between each of the blower motor switch input terminals of the blower motor resistor and the resistor output terminal. In each case there should be continuity. If OK, repair the instrument panel wire harness circuits between the blower motor switch and the blower motor resistor or the blower motor pigtail wires as required. If not OK, replace the faulty blower motor resistor.

Scheme 33

1. Disconnect and isolate the battery negative cable.
2. Open the glove box.
3. Flex both sides of the glove box bin inward near the top far enough for the rubber glove box stop bumpers to clear the sides of the glove box opening, then roll the glove box downward.
4. Reach through the glove box opening to access and disconnect the instrument panel wire harness connector for the blower motor resistor from the resistor connector receptacle (Scheme 33)
5. Reach through the glove box opening to access and disconnect the blower motor pigtail wire connector from the resistor connector receptacle.
6. Remove the two screws that secure the blower motor resistor to the evaporator housing.
7. Remove the blower motor resistor from the evaporator housing.

1. Position the blower motor resistor into the evaporator housing.
2. Install and tighten the two screws that secure the blower motor resistor to the evaporator housing. Tighten the screws to 2 N.m (17 in. lbs.).
3. Reconnect the blower motor pigtail wire connector to the blower motor resistor connector receptacle.
4. Reconnect the instrument panel wire harness connector for the blower motor resistor to the resistor connector receptacle.
5. Flex both sides of the glove box bin inward near the top far enough for the rubber glove box stop bumpers to clear the sides of the glove box opening, then roll the glove box upward.
6. Close and latch the glove box.
7. Reconnect the battery negative cable.

The compressor clutch assembly consists of a stationary electromagnetic coil with a zener diode, a hub bearing and pulley assembly, and a clutch plate (Scheme 34) 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 keyed or splined to the compressor shaft, and secured with a bolt.

Scheme 34

The compressor clutch plate and pulley unit, or the clutch coil are available for separate service replacement. The clutch coil zener diode is integral to the clutch coil pigtail wire and connector and, if faulty or damaged, the clutch electromagnetic coil unit must be replaced.

The compressor clutch 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 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.

A zener diode is connected in parallel with the clutch electromagnetic coil. This diode controls the dissipation of voltage induced into the coil windings by the collapsing of the electromagnetic fields that occurs when the compressor clutch is disengaged. The zener diode dissipates this induced voltage by regulating a current path to ground. This arrangement serves to protect other circuits and components from potentially damaging voltage spikes in the vehicle electrical system that might occur if the voltage induced in the clutch coil windings could not be dissipated.

The compressor clutch engagement is controlled by several components: the heater-A/C controls in the passenger compartment, the A/C pressure transducer on the liquid line, the evaporator temperature sensor on the expansion valve, the Powertrain Control Module (PCM) in the engine compartment, and the compressor clutch relay in the Intelligent Power Module (IPM). The PCM may delay compressor clutch engagement for up to thirty seconds. (Refer to PCM OPERATION ).

STANDARD PROCEDURE - COMPRESSOR CLUTCH AIR GAP

If a new clutch plate and/or clutch pulley are being used, the air gap between the clutch plate and clutch pulley must be checked using the following procedure

1. Using feeler gauges, measure the air gap between the clutch plate and the clutch pulley friction surfaces.
2. If the air gap is not between 0.5 and 0.9 mm (0.020 and 0.035 in.), add or subtract shims until the desired air gap is obtained.

Note. The shims may compress after tightening the compressor shaft bolt. Check the air gap in four or more places on the clutch plate to verify that the air gap is still correct. Spin the clutch pulley before making the final air gap check.

STANDARD PROCEDURE - COMPRESSOR CLUTCH BREAK-IN

After a new compressor clutch has been installed, check that the compressor clutch coil is performing to specifications. (Refer to COMPRESSOR CLUTCH COIL ). If the clutch coil is performing to specifications, perform the compressor clutch break-in procedure. This procedure (burnishing) will seat the opposing friction surfaces and provide a higher compressor clutch torque capability.

1. Set the heater-A/C controls to the A/C mode, with the blower switch in the highest speed position.
2. Start the engine and hold the engine speed at 1500 to 2000 rpm.
3. Cycle the compressor clutch On and Off about twenty times (seven seconds On, then seven seconds Off).

The refrigerant system can remain fully charged during compressor clutch, pulley, or coil replacement. Although the compressor assembly must be removed from its mounting, the compressor clutch can be service with the compressor in the vehicle.

Scheme 35

Scheme 36

Scheme 37

1. Disconnect and isolate the battery negative cable.
2. Raise and support the vehicle.
3. Remove the serpentine drive belt. (Refer to DRIVE BELTS - 2.4L - REMOVAL ) or (Refer to DRIVE BELTS - 3.3/3.8L - REMOVAL ).
4. Disconnect the engine wire harness connector for the compressor clutch coil from the clutch coil pigtail wire connector on the top of the compressor.
5. On models with the 3.3L and 3.8L engines, disengage the retainer on the engine wire harness compressor clutch coil take out from the bracket on the top of the compressor.
6. On models with the 2.4L engine, remove all of the compressor mounting screws except the upper left (rear of the compressor) screw, which should only be loosened. Allow the front (pulley end) of the compressor to tilt downward far enough to access the clutch for removal, then tighten the loosened upper left compressor mounting screw.
7. On models with the 3.3L and 3.8L engines, remove the three screws and one nut that secure the compressor to the engine. Disengage the mounting ear at the front of the compressor from the stud on the engine, allow the front (pulley end) of the compressor to tilt downward far enough to access the clutch for removal, then reinstall and tighten the upper left compressor mounting screw.
8. Remove the compressor shaft bolt (Scheme 35) If necessary, a band-type oil filter wrench or a strap wrench can be placed around the clutch plate to aid in bolt removal.
9. Tap the clutch plate lightly with a plastic hammer and remove the clutch plate and shim(s) from the compressor shaft (Scheme 36) Be certain not to lose the shim or shims.
10. Using snap ring pliers (Special Tool C-4574 or equivalent), remove the external snap ring that secures the pulley to the front cover of the compressor, then slide the pulley off of the compressor (Scheme 37)
11. Remove the screw that secures the clutch coil pigtail wire connector bracket and ground clip to the top of the compressor housing.
12. Using snap ring pliers (Special Tool C-4574 or equivalent), remove the external snap ring that secures the clutch coil to the front cover of the compressor housing, then slide the clutch coil off of the compressor (Scheme 38)

INSPECTION - COMPRESSOR CLUTCH/COIL

Compressor clutch components should always be inspected closely before they are reinstalled. The clutch plate and clutch pulley are mated at the factory using a burnishing operation. No attempt should be made to separately replace the compressor clutch pulley or clutch plate. The clutch coil may be serviced separately.

1. Examine the friction surfaces of the clutch pulley and the clutch plate for wear. The clutch pulley and clutch plate should be replaced if there is excessive wear or scoring.
2. Examine the friction surfaces of the clutch pulley and the clutch plate for oil contamination. If the friction surfaces are oily, the clutch pulley and clutch plate should be replaced. Also inspect the shaft and nose area of the compressor for oil. Remove the felt packing from around the compressor shaft in the compressor front cover. If the felt is saturated with oil, the compressor front shaft seal is leaking and the compressor will also have to be replaced.
3. Check the clutch pulley bearing for roughness or excessive leakage of grease. Replace the clutch pulley and clutch plate if the bearing is faulty.

The refrigerant system can remain fully charged during compressor clutch, pulley, or coil replacement. Although the compressor assembly must be removed from its mounting, the compressor clutch can be service with the compressor in the vehicle.

1. Align the dowel pin on the back of the clutch coil with the hole in the compressor front cover, and position the clutch coil onto the compressor. Be certain that the clutch coil pigtail wires are properly oriented and routed so that they are not pinched between the compressor front cover and the clutch coil.
2. Using snap ring pliers (Special Tool C-4574 or equivalent), install the external snap ring that secures the clutch coil to the front cover of the compressor. The bevel side of the snap ring must face outward and both snap ring eyelets must be oriented to the right or the left of the clutch coil dowel pin location on the compressor. Be certain that the snap ring is fully and properly seated in the groove.
3. Install and tighten the screw that secures the clutch coil pigtail wire connector bracket and ground clip to the top of the compressor housing.
4. Install the pulley onto the front cover of the compressor. If necessary, tap the pulley gently with a block of wood placed on the pulley friction surface (Scheme 39)
5. Using snap ring pliers (Special Tool C-4574 or equivalent), install the external snap ring (bevel side facing outward) that secures the clutch pulley to the front cover of the compressor. Be certain that the snap ring is fully and properly seated in the groove.
6. If the original clutch plate and clutch pulley are to be reused, reinstall the original shim(s) on the compressor shaft against the shoulder. If a new clutch plate and/or clutch pulley are being used, install a trial stack of shims 1.0 mm (0.040 in.) thick on the compressor shaft against the shoulder.
7. Install the clutch plate onto the compressor shaft.
8. Install and tighten the compressor shaft nut. If necessary, a band-type oil filter wrench or a strap wrench can be placed around the clutch plate to aid in bolt tightening. Tighten the bolt to 17.5 N.m (155 in. lbs.).
9. If a new clutch plate and/or clutch pulley are being installed, the air gap between the clutch plate and clutch pulley must be checked. (Refer to «STANDARD PROCEDURE»(/dodge/grand-caravan/iv-2000-2007/remont/automatic-hvac-system/#automatic-hvac-systems-controls-front) ).
10. On models with the 2.4L engine only, loosely install the four screws that secure the compressor to the mounting bracket on the engine. Tighten the screws to 28 N.m (21 ft. lbs.).
11. On models with the 3.3L and 3.8L engines only, loosely install the two screws and two nuts that secure the compressor to the engine. Tighten each of the fasteners using the following sequence to 54 N.m (40 ft. lbs.). The upper nut at the front of the compressor. The lower nut at the front of the compressor. The upper screw at the rear of the compressor. The lower screw at the rear of the compressor.
12. On models with the 3.3L and 3.8L engines only, engage the retainer on the engine wire harness compressor clutch coil take out with the bracket on the top of the compressor.
13. Reconnect the engine wire harness connector for the compressor clutch coil to the coil pigtail wire connector on the top of the compressor.
14. Reinstall the serpentine accessory drive belt onto the front of the engine. (Refer to DRIVE BELTS - 2.4L - INSTALLATION ) or (Refer to DRIVE BELTS - 3.3L/3.8L - INSTALLATION ).
15. Lower the vehicle.
16. Reconnect the battery negative cable.
17. If a new clutch plate and/or clutch pulley are being installed, the new clutch components must be burnished. (Refer to «STANDARD PROCEDURE»(/dodge/grand-caravan/iv-2000-2007/remont/automatic-hvac-system/#automatic-hvac-systems-controls-front) ).

DIAGNOSIS AND TESTING - COMPRESSOR CLUTCH COIL

The air conditioning compressor clutch coil electrical circuit is controlled by the Powertrain Control Module (PCM) through the compressor clutch relay, which is located in the Intelligent Power Module (IPM) in the engine compartment near the battery. Begin testing of a suspected compressor clutch coil problem by performing the preliminary checks.

PRELIMINARY CHECKS

1. If the compressor clutch will not engage, verify the refrigerant charge level. (Refer to REFRIGERANT - DIAGNOSIS AND TESTING - REFRIGERANT CHARGE LEVEL ). If the refrigerant charge level is OK, go to Step 2. If the refrigerant charge level is not OK, adjust the refrigerant charge as required.
2. If the a/c compressor clutch still will not engage, disconnect the headlamp and dash wire harness connector for the A/C pressure transducer and check for battery current at the connector with the engine running and the heater-A/C control set to the A/C mode. If OK, go to TESTS. If not OK, use a DRBIII(R) scan tool to perform further diagnosis. Refer to the appropriate diagnostic information.

TESTS

1. Verify the battery state of charge. (Refer to BATTERY - DIAGNOSIS AND TESTING ).
2. Connect an ammeter (0 to 10 ampere scale selected) in series with the clutch coil feed terminal. Connect a voltmeter (0 to 20 volt scale selected) to measure voltage across the battery and the clutch coil.
3. With the heater-A/C control in the A/C mode and the blower at low speed, start the engine and allow it to run at a normal idle speed.
4. The compressor clutch should engage immediately, and the clutch coil voltage should be within two volts of the battery voltage. If the coil voltage is not within two volts of battery voltage, test the clutch coil feed circuit for excessive voltage drop. If the compressor clutch does not engage, use a DRBIII(R) scan tool to perform further diagnosis. Refer to the appropriate diagnostic information.
5. With the ambient temperature at 21° C (70° F), the compressor clutch coil is acceptable if the current draw is 2.0 to 3.7 amperes at 11.5 to 12.5 volts at the clutch coil. If the voltage is more than 12.5 volts, add electrical loads by turning on electrical accessories until the voltage reads below 12.5 volts. If the compressor clutch coil current reading is zero, the coil is open and must be replaced. If the compressor clutch coil current reading is four amperes or more, the coil is shorted and must be replaced.

The compressor clutch relay (Scheme 40) 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

1. The common feed terminal (30) receives a battery current input from a fuse in the IPM through a fused B(+) circuit at all times.
2. 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.
3. 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.
4. 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.
5. 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.

DIAGNOSIS AND TESTING - COMPRESSOR CLUTCH RELAY

The compressor clutch relay (Scheme 40) 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. Remove the relay from the IPM to perform the following tests

Scheme 38

1. A relay in the de-energized position should have continuity between terminals 87A and 30, and no continuity between terminals 87 and 30. If OK, go to Step 2. If not OK, replace the faulty relay.
2. Resistance between terminals 85 and 86 (electromagnet) should be 75 + 5 ohms. If OK, go to Step 3. If not OK, replace the faulty relay.
3. Connect a battery to terminals 85 and 86. There should now be continuity between terminals 30 and 87, and no continuity between terminals 87A and 30. If OK, use a DRBIII(R) scan tool to perform further diagnosis of the relay circuits. Refer to the appropriate diagnostic information. If not OK, replace the faulty relay.

COMPRESSOR CLUTCH RELAY TERMINAL LEGEND

1. Disconnect and isolate the battery negative cable.
2. Unlatch and remove the cover from the Intelligent Power Module (IPM).
3. See the fuse and relay layout map molded into the inner surface of the IPM cover for compressor clutch relay identification and location.
4. Remove the compressor clutch relay from the IPM by pulling it straight up.

1. See the fuse and relay layout map molded into the inner surface of the Intelligent Power Module (IPM) cover for compressor clutch relay identification and location.
2. Position the compressor clutch relay to the proper receptacle in the IPM.
3. Align the compressor clutch relay terminals with the terminal cavities in the IPM relay receptacle.
4. Push down firmly on the compressor clutch relay until the terminals are fully seated in the terminal cavities in the IPM receptacle.
5. Install and latch the cover onto the IPM.
6. Reconnect the battery negative cable.

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 (Scheme 41) 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.

Scheme 39

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 DRBIII(R) scan tool. Refer to the appropriate diagnostic information.

1. Disconnect and isolate the battery negative cable.
2. Remove the air cleaner housing from the right side of the engine compartment.
3. Remove the windshield wiper assembly from the vehicle (Refer to WIPER MODULE - REMOVAL ).
4. Remove the temperature sensor attaching screw from the expansion valve.
5. Pull the evaporator temperature sensor away from the expansion valve far enough to access the red release ring on the wiring connector. Push the red ring toward the connector to release lock and remove the HVAC wire harness connector from the temperature sensor.
6. Remove the evaporator temperature sensor from the engine compartment. Please note that any grease removed with the old temperature sensor must be replaced, failure to do so could result in poor a/c performance.

1. Position the evaporator temperature sensor into the right rear corner of the engine compartment. Please make sure any grease removed with the old sensor has been replaced before the new sensor is installed, failure to do so could lead to poor a/c performance.
2. Reconnect the HVAC wire harness connector for the evaporator temperature sensor to the sensor connector receptacle.
3. Position the evaporator temperature sensor onto the top of the expansion valve with the sensor probe inserted into the well in the expansion valve.
4. Install the temperature sensor retaining screw and tighten.
5. Install the window wiper assembly to the vehicle (Refer to WIPER MODULE - INSTALLATION ).
6. Reinstall the air cleaner housing into the right side of the engine compartment.
7. Reconnect the battery negative cable.
8. Run the HVAC Cool Down test to verify system is operating properly (Refer to AIR CONDITIONING - DIAGNOSIS AND TESTING ).

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 (Scheme 42) 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.

Scheme 40

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 DRBIII(R) scan tool. Refer to the appropriate diagnostic information.

The mode door actuator is a reversible, 12-volt Direct Current (DC), servo motor (Scheme 43) 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.

Scheme 41

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 DRBIII(R) scan tool. Refer to the appropriate diagnostic information.

Scheme 42

1. Disconnect and isolate the battery negative cable.
2. Remove the silencer from beneath the driver side end of the instrument panel. (Refer to INSTRUMENT PANEL SILENCER - REMOVAL ).
3. Disconnect the HVAC wire harness connector for the mode door actuator from the actuator connector receptacle (Scheme 44)
4. Remove the two screws that secure the mode door actuator to the distribution housing.
5. Remove the mode door actuator from the distribution housing.

1. Position the mode door actuator onto the heater/AC housing. If necessary, rotate the actuator slightly to align the splines on the actuator output shaft with those in the mode door linkage.
2. Install and tighten the two screws that secure the mode door actuator to the distribution housing. Tighten the screws to 2 N.m (17 in. lbs.).
3. Reconnect the HVAC wire harness connector for the mode door actuator to the actuator connector receptacle.
4. Reinstall the silencer under the driver side end of the instrument panel. (Refer to INSTRUMENT PANEL SILENCER - INSTALLATION ).
5. Reconnect the battery negative cable.
6. Perform the heater-A/C control calibration procedure. (Refer to «STANDARD PROCEDURE - HEATER-A/C CONTROL CALIBRATION»(/dodge/grand-caravan/iv-2000-2007/remont/automatic-hvac-system/#automatic-hvac-systems-controls-front__standard-procedure-heater-ac-control-calibration) ).

A blower power module is used on this model when it is equipped with the optional Automatic Temperature Control (ATC) (Scheme 45) 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.

Scheme 43

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 DRBIII(R) scan tool. Refer to the appropriate diagnostic information.

1. Disconnect and isolate the battery negative cable.
2. Open the glove box.
3. Flex both sides of the glove box bin inward near the top far enough for the rubber glove box stop bumpers to clear the sides of the glove box opening, then roll the glove box downward.
4. Reach through the glove box opening to access and disconnect the instrument panel wire harness connector for the power module from the module connector receptacle.
5. Reach through the glove box opening to access and disconnect the blower motor pigtail wire connector from the power module connector receptacle.
6. Remove the two screws that secure the power module to the evaporator housing.
7. Remove the power module from the evaporator housing.

1. Position the power module into the evaporator housing.
2. Install and tighten the two screws that secure the power module to the evaporator housing. Tighten the screws to 2 N.m (18 in. lbs.).
3. Reconnect the blower motor pigtail wire connector to the power module connector receptacle.
4. Reconnect the instrument panel wire harness connector for the power module to the module connector receptacle.
5. Flex both sides of the glove box bin inward near the top far enough for the rubber glove box stop bumpers to clear the sides of the glove box opening, then roll the glove box upward.
6. Close and latch the glove box.
7. Reconnect the battery negative cable.

The recirculation door actuator is a reversible, 12-volt Direct Current (DC), servo motor see scheme 24 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.

Scheme 44

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 DRBIII(R) scan tool. Refer to the appropriate diagnostic information.

Scheme 45

1. Disconnect and isolate the battery negative cable.
2. Pull the carpet on the passenger side front floor away from the dash panel far enough to access the recirculation door actuator.
3. Disconnect the HVAC wire harness connector for the recirculation door actuator from the actuator connector receptacle see scheme 25
4. Remove the two screws that secure the recirculation door actuator to the lower intake air housing.
5. Remove the recirculation door actuator from the lower intake air housing.

1. Position the recirculation door actuator onto the lower intake air housing. If necessary, rotate the actuator slightly to align the splines on the actuator output shaft with those in the recirculation air door.
2. Install and tighten the two screws that secure the recirculation door actuator to the lower intake air housing. Tighten the screws to 2 N.m (17 in. lbs.).
3. Reconnect the HVAC wire harness connector for the recirculation door actuator to the actuator connector receptacle.
4. Reposition the carpet on the passenger side front floor back up to the dash panel.
5. Reconnect the battery negative cable.
6. Perform the heater-A/C control calibration procedure. (Refer to «STANDARD PROCEDURE - HEATER-A/C CONTROL CALIBRATION»(/dodge/grand-caravan/iv-2000-2007/remont/automatic-hvac-system/#automatic-hvac-systems-controls-front__standard-procedure-heater-ac-control-calibration) ).

See also:
• STANDARD PROCEDURE - HEATER-A/C CONTROL CALIBRATION
• COMPRESSOR CLUTCH COIL