Automatic HVAC Systems - Controls - Rear Dodge Grand Caravan IV

Scheme 46

Scheme 47

1. Disconnect and isolate the battery negative cable.
2. Using a trim stick or another suitable wide flat bladed tool, gently pry the top edge of the rear heater-A/C control bezel away from the headliner far enough to release the two snap clip retainers (Scheme 46)
3. Pull the rear heater-A/C control and bezel unit rearward far enough to access the headliner wire harness connector on the back of the control.
4. Disconnect the headliner wire harness connector for the rear heater-A/C control from the control connector receptacle.
5. Remove the rear heater-A/C control from the headliner.
6. Remove the three screws that secure the rear heater-A/C control to the bezel (Scheme 47)
7. Remove the rear heater-A/C control from the bezel.

INSTALLATION

1. Position the rear heater-A/C control onto the bezel.
2. Install and tighten the three screws that secure the rear heater-A/C control to the bezel. Tighten the screws to 2 N.m (17 in. lbs.).
3. Position the rear heater-A/C control and bezel unit to the headliner.
4. Reconnect the headliner wire harness connector for the rear heater-A/C control to the control connector receptacle.
5. Insert the locator tabs on the back of the rear heater-A/C control and bezel unit over the forward edge of the headliner opening for the control.
6. Slide the rear heater-A/C control and bezel unit forward far enough to align the snap clips on the bezel with the snap clip receptacles on the retainer above the headliner.
7. Using hand pressure, press the top edge of the rear heater-A/C control bezel upward until the two snap clips are fully seated in their receptacles.
8. Reconnect the battery negative cable.
9. Using the DRB-III(R) reset the Rear Temperature Selector calibration values.
10. Verify that the Actuator Calibration of the Front Control has passed. If an Actuator Calibration has not passed correct any errors before proceeding further.
11. Rotate the Rear Temperature Selector counter clockwise to the Cold Position, allow the Selector to remain in the Cold Position for 5 seconds.
12. Rotate the Rear Temperature Selector Clockwise to the Hot Position, allow the Selector to remain in the Cold Position for 5 seconds.
13. Calibration is now complete.

DESCRIPTION

The blend door actuator is a reversible, 12-volt Direct Current (DC), servo motor (Scheme 48) 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.

Scheme 48

OPERATION

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

Scheme 49

1. Disconnect and isolate the battery negative cable.
2. Remove the right quarter trim panel and right D-pillar trim panel from the quarter inner panel. (Refer to QUARTER TRIM PANEL - REMOVAL ).
3. Remove the two screws that secure the top of the quarter trim panel attaching bracket to the quarter inner panel.
4. Remove the screw that secures the back of the rear heater-A/C unit housing to the right D-pillar.
5. Remove the screw that secures the front of the rear heater-A/C unit housing to the right quarter inner panel.
6. Carefully pull the top of the rear heater-A/C unit housing away from the right quarter inner panel far enough to reach between the rear heater-A/C unit housing and the quarter inner panel to access the blend door actuator (Scheme 49)
7. Remove the two screws that secure the blend door actuator to the rear heater-A/C unit housing.
8. Pull the blend door actuator away from the rear heater-A/C unit housing far enough to disengage the actuator output shaft from the blend air door pivot.
9. Raise the blend door actuator far enough to access and disconnect the rear HVAC wire harness connector for the actuator from the actuator connector receptacle.
10. Remove the blend door actuator from between the rear heater-A/C unit housing and the quarter inner panel.

1. Position the blend door actuator between the rear heater-A/C unit housing and the quarter inner panel.
2. Reconnect the rear HVAC wire harness connector for the blend door actuator to the actuator connector receptacle.
3. Position the blend door actuator onto the rear heater-A/C unit housing. If necessary, rotate the actuator slightly to align the splines on the actuator output shaft with those in the blend air door pivot.
4. Install and tighten the two screws that secure the blend door actuator to the rear heater-A/C unit housing. Tighten the screws to 2 N.m (18 in. lbs.).
5. Push the top of the rear heater-A/C unit housing back into position against the right quarter inner panel.
6. Install and tighten the screw that secures the front of the rear heater-A/C unit housing to the right quarter inner panel. Tighten the screw to 11 N.m (97 in. lbs.).
7. Install and tighten the screw that secures the back of the rear heater-A/C unit housing to the right D-pillar. Tighten the screw to 11 N.m (97 in. lbs.).
8. Install and tighten the two screws that secure the top of the quarter trim panel attaching bracket to the quarter inner panel. Tighten the screws to 1.7 N.m (15 in. lbs.).
9. Reinstall the right quarter trim panel and right D-pillar trim panel onto the quarter inner panel. (Refer to QUARTER TRIM PANEL - INSTALLATION ).
10. Reconnect the battery negative cable.
11. Perform the heater-A/C control calibration procedure. (Refer to A/C-HEATER CONTROL - STANDARD PROCEDURE - HEATER-A/C CONTROL CALIBRATION ).

The blower motor relay (Scheme 50) 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

1. 30 (Common Feed) - This terminal is connected to the movable contact point of the relay.
2. 85 (Coil Ground) - This terminal is connected to the ground feed side of the relay control coil.
3. 86 (Coil Battery) - This terminal is connected to the battery feed side of the relay control coil.
4. 87 (Normally Open) - This terminal is connected to the normally open fixed contact point of the relay.
5. 87A (Normally Closed) - This terminal is connected to the normally closed fixed contact point of the relay.

Scheme 50

BLOWER MOTOR RELAY TERMINAL LEGEND

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

1. 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.
2. The coil battery terminal (86) receives a battery current input from the battery through a B(+) circuit at all times.
3. 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.
4. 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 rear blower motor relay (Scheme 51) 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 rear blower motor relay identification and location. Remove the relay from the IPM to perform the following tests

Scheme 51

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 52

1. Disconnect and isolate the battery negative cable.
2. Unlatch and remove the cover from the Intelligent Power Module (IPM) (Scheme 52)
3. See the fuse and relay layout map molded into the inner surface of the IPM cover for rear blower motor relay identification and location.
4. Remove the rear blower motor relay from the IPM.

1. See the fuse and relay layout map molded into the inner surface of the Intelligent Power Module (IPM) cover for rear blower motor relay identification and location.
2. Position the rear blower motor relay to the proper receptacle in the IPM.
3. Align the rear blower motor relay terminals with the terminal cavities in the IPM relay receptacle.
4. Push down firmly on the rear 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 53) 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 is an electrical circuit board. 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.

Scheme 53

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 an electrical circuit board 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.

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 rear HVAC wire harness connector for the blower motor resistor from the resistor connector receptacle.
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 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.

REMOVAL

Scheme 54

1. Disconnect and isolate the battery negative cable.
2. Remove the right quarter trim panel and right D-pillar trim panel from the quarter inner panel. (Refer to QUARTER TRIM PANEL - REMOVAL ).
3. Disconnect the rear HVAC wire harness connector for the blower motor resistor from the resistor connector receptacle (Scheme 54)
4. Remove the two screws that secure the blower motor resistor to the rear heater-A/C unit housing.
5. Remove the blower motor resistor from the rear heater-A/C unit housing.

1. Position the blower motor resistor into the rear heater-A/C unit housing.
2. Install and tighten the two screws that secure the blower motor resistor to the rear heater-A/C unit housing. Tighten the screws to 2 N.m (17 in. lbs.).
3. Reconnect the rear HVAC wire harness connector for the blower motor resistor to the resistor connector receptacle.
4. Reinstall the right quarter trim panel and right D-pillar trim panel onto the quarter inner panel. (Refer to QUARTER TRIM PANEL - INSTALLATION ).
5. Reconnect the battery negative cable.

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

Scheme 55

1. Disconnect and isolate the battery negative cable.
2. Remove the right quarter trim panel and right D-pillar trim panel from the quarter inner panel. (Refer to QUARTER TRIM PANEL - REMOVAL ).
3. Remove the two screws that secure the top of the quarter trim panel attaching bracket to the quarter inner panel.
4. Remove the screw that secures the back of the rear heater-A/C unit housing to the right D-pillar.
5. Remove the screw that secures the front of the rear heater-A/C unit housing to the right quarter inner panel.
6. Carefully pull the top of the rear heater-A/C unit housing away from the right quarter inner panel far enough to reach between the rear heater-A/C unit housing and the quarter inner panel to access the mode door actuator (Scheme 55)
7. Remove the two screws that secure the mode door actuator to the rear heater-A/C unit housing.
8. Pull the mode door actuator away from the rear heater-A/C unit housing far enough to disengage the actuator output shaft from the mode door linkage.
9. Raise the mode door actuator far enough to access and disconnect the rear HVAC wire harness connector for the actuator from the actuator connector receptacle.
10. Remove the mode door actuator from between the rear heater-A/C unit housing and the quarter inner panel.

1. Position the mode door actuator between the rear heater-A/C unit housing and the quarter inner panel.
2. Reconnect the rear HVAC wire harness connector for the mode door actuator to the actuator connector receptacle.
3. Position the mode door actuator onto the rear heater-A/C unit housing. If necessary, rotate the actuator slightly to align the splines on the actuator output shaft with those in the mode door linkage.
4. Install and tighten the two screws that secure the mode door actuator to the rear heater-A/C unit housing. Tighten the screws to 2 N.m (18 in. lbs.).
5. Push the top of the rear heater-A/C unit housing back into position against the right quarter inner panel.
6. Install and tighten the screw that secures the front of the rear heater-A/C unit housing to the right quarter inner panel. Tighten the screw to 11 N.m (97 in. lbs.).
7. Install and tighten the screw that secures the back of the rear heater-A/C unit housing to the right D-pillar. Tighten the screw to 11 N.m (97 in. lbs.).
8. Install and tighten the two screws that secure the top of the quarter trim panel attaching bracket to the quarter inner panel. Tighten the screws to 1.7 N.m (15 in. lbs.).
9. Reinstall the right quarter trim panel and right D-pillar trim panel onto the quarter inner panel. (Refer to QUARTER TRIM PANEL - INSTALLATION ).
10. Reconnect the battery negative cable.
11. Perform the heater-A/C control calibration procedure. (Refer to A/C-HEATER CONTROL - STANDARD PROCEDURE - HEATER-A/C CONTROL CALIBRATION ).

A blower power module is used on this model when it is equipped with the optional Automatic Temperature Control (ATC) (Scheme 56) 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.

Scheme 56

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

Scheme 57

1. Disconnect and isolate the battery negative cable.
2. Remove the right quarter trim panel and right D-pillar trim panel from the quarter inner panel. (Refer to QUARTER TRIM PANEL - REMOVAL ).
3. Disconnect the rear HVAC wire harness connector for the blower power module from the resistor connector receptacle (Scheme 57)
4. Disconnect the blower motor pigtail wire connector from the blower power module connector receptacle.
5. Remove the two screws that secure the blower power module to the rear heater-A/C unit housing.
6. Remove the blower power module from the rear heater-A/C unit housing.

1. Position the blower power module into the rear heater-A/C unit housing.
2. Install and tighten the two screws that secure the blower power module to the rear heater-A/C unit housing. Tighten the screws to 2 N.m (17 in. lbs.).
3. Reconnect the blower motor pigtail wire to the blower power module connector receptacle.
4. Reconnect the rear HVAC wire harness connector for the blower power module to the module connector receptacle.
5. Reinstall the right quarter trim panel and right D-pillar trim panel onto the quarter inner panel. (Refer to QUARTER TRIM PANEL - INSTALLATION ).
6. Reconnect the battery negative cable.