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Rear Climate Control Acura MDX II

Automatic HVAC System 23 illustrations ~2499 words

Scheme 233

Scheme 233: Component Location Index
Scheme 233: Component Location Index

Scheme 234

Scheme 234: Rear Climate Control Door Positions
Scheme 234: Rear Climate Control Door Positions

Scheme 235

Scheme 235: Rear A/C Line Replacement
Scheme 235: Rear A/C Line Replacement

Scheme 236

Scheme 236: Rear Heater Line Replacement
Scheme 236: Rear Heater Line Replacement

Scheme 237

Scheme 237: Rear Evaporator Temperature Sensor Test
Scheme 237: Rear Evaporator Temperature Sensor Test

Scheme 238

Scheme 238
Scheme 238
  1. Remove the rear evaporator temperature sensor (see «REAR EVAPORATOR TEMPERATURE SENSOR REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#rear-climate-control__rear-evaporator-temperature-sensor-replacement) ).
  2. Dip the sensor in ice water, and measure the resistance between its terminals.
  3. Then pour warm water on the sensor, and check for a change in the resistance.
  4. Compare the resistance readings with the specifications shown in the graph; the resistance should be within the specifications.
  5. If the resistance is not as specified, replace the rear evaporator temperature sensor (see «REAR EVAPORATOR TEMPERATURE SENSOR REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#rear-climate-control__rear-evaporator-temperature-sensor-replacement) ).

Rear Evaporator Temperature Sensor Replacement

SRS components are located in this area. Review the SRS component locations (see COMPONENT LOCATION INDEX ) and the precautions and procedures (see PRECAUTIONS AND PROCEDURES ) before doing repairs or service.

Scheme 239

Scheme 239: Rear Evaporator Temperature Sensor Replacement
Scheme 239: Rear Evaporator Temperature Sensor Replacement
  1. Remove the center console (see «CENTER CONSOLE REMOVAL/INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exteriorinterior-trim/#consoles__center-console-removalinstallation) ).
  2. Disconnect the 2P connector (A) from the rear evaporator temperature sensor (B), then remove the connector clip (C). Remove the self-tapping screw and the rear evaporator temperature sensor from the rear HVAC unit.
  3. Install the sensor in the reverse order of removal.

Rear Power Transistor Test

SRS components are located in this area. Review the SRS component locations (see COMPONENT LOCATION INDEX ) and the precautions and procedures (see PRECAUTIONS AND PROCEDURES ) before doing repairs or service.

Scheme 240

Scheme 240: Rear Power Transistor Test
Scheme 240: Rear Power Transistor Test

Scheme 241

Scheme 241
Scheme 241
  1. Remove the driver's seat (see «FRONT SEAT REMOVAL/INSTALLATION»(/acura/mdx/ii-2006-2010/remont/seats/#seats__front-seat-removalinstallation) ).
  2. Remove the driver's center console trim (see «CENTER CONSOLE REMOVAL/INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exteriorinterior-trim/#consoles__center-console-removalinstallation) ).
  3. Disconnect the 4P connector from the rear power transistor.
  4. Measure the resistance between the No. 3 and No. 4 terminals of the rear power transistor. It should be about 1.5 kohms. If the resistance is within the specifications, go to step 5. If the resistance is not within the specifications, replace the rear power transistor. NOTE: Also check the rear blower motor. Rear power transistor failure can be caused by a defective rear blower motor.
  5. Carefully release the lock tab on the No. 1 terminal (BLU) (A) in the 4P connector, then remove the terminal and insulate it from body ground.
  6. Reconnect the 4P connector to the rear power transistor.
  7. Make sure the BLU wire is completely isolated, then supply 12 V to the No. 1 cavity with a jumper wire.
  8. Turn the ignition switch to ON (II), and check that the rear blower motor runs at high speed. If the rear blower motor does not run, replace the rear power transistor. NOTE: A faulty rear blower motor can cause the rear power transistor to fail. If the rear power transistor is replaced, also check the rear blower motor for binding, and replace it if necessary. If the rear blower motor runs, the rear power transistor is OK.

Rear Air Mix Control Motor Test

Note. Before testing, check for HVAC DTCs (see GENERAL TROUBLESHOOTING INFORMATION ).

Scheme 242

Scheme 242: Rear Air Mix Control Motor Test
Scheme 242: Rear Air Mix Control Motor Test
  1. Disconnect the 7P connector from the rear air mix control motor. NOTE: Incorrectly applying power and ground to the rear air mix control motor will damage it. Follow the instructions carefully.
  2. Connect battery power to the No. 1 terminal of the rear air mix control motor, and ground the No. 2 terminal; the rear air mix control motor should run, and stop at Max Hot. If it doesn't, reverse the connections; the rear air mix control motor should run, and stop at Max Cool. When the rear air mix control motor stops running, disconnect battery power immediately.
  3. If the rear air mix control motor did not run in step 2 , remove it, then check the rear air mix control linkage and door for smooth movement. If the linkage and door move smoothly, replace the rear air mix control motor (see «REAR AIR MIX CONTROL MOTOR REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#rear-climate-control__rear-air-mix-control-motor-replacement) ). If the linkage or door sticks or binds, repair them as needed. If the rear air mix control motor runs smoothly, go to step 4.
  4. Measure the resistance between the No. 5 and No. 7 terminals. It should be between 4.2 to 7.8 kohms.
  5. Reconnect the rear air mix control motor 7P connector, then turn the ignition switch to ON (II).
  6. Using the backprobe set, measure the voltage between the No. 3 and No. 7 terminals. Max Cool: about 0.5 V Max Hot: about 4.5 V
  7. If either the resistance or voltage readings are not as specified, replace the rear air mix control motor (see «REAR AIR MIX CONTROL MOTOR REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#rear-climate-control__rear-air-mix-control-motor-replacement) ).

Rear Air Mix Control Motor Replacement

SRS components are located in this area. Review the SRS component locations (see COMPONENT LOCATION INDEX ) and the precautions and procedures (see PRECAUTIONS AND PROCEDURES ) before doing repairs or service.

Scheme 243

Scheme 243: Rear Air Mix Control Motor Replacement
Scheme 243: Rear Air Mix Control Motor Replacement
  1. Remove the center console (see «CENTER CONSOLE REMOVAL/INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exteriorinterior-trim/#consoles__center-console-removalinstallation) ).
  2. Disconnect the 7P connector (A) from the rear air mix control motor (B). Remove the self-tapping screws and the rear air mix control motor from the HVAC unit.
  3. Install the motor in the reverse order of removal. Make sure the pin on the motor is properly engaged with the linkage. After installation, make sure the motor runs smoothly.

Rear Mode Control Motor Test

Note. Before testing, check for HVAC DTCs (see GENERAL TROUBLESHOOTING INFORMATION ).

Scheme 244

Scheme 244: Rear Mode Control Motor Test
Scheme 244: Rear Mode Control Motor Test
  1. Disconnect the 7P connector from the rear mode control motor. NOTE: Incorrectly applying power and ground to the rear mode control motor will damage it. Follow the instructions carefully.
  2. Connect battery power to the No. 1 terminal of the rear mode control motor, and ground the No. 5 and No. 7 terminals; the rear mode control motor should run smoothly. To avoid damaging the rear mode control motor, do not reverse power and ground. Disconnect the No. 5 or No. 7 terminals from ground; the rear mode control motor should stop at Vent (when the No. 5 terminal is disconnected) or Heat (when the No. 7 terminal is disconnected). Don't cycle the rear mode control motor for a long time.
  3. If the rear mode control motor did not run in step 2 , remove it, then check the rear mode control linkage and door for smooth movement. If the linkage and door move smoothly, replace the rear mode control motor (see «REAR MODE CONTROL MOTOR REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#rear-climate-control__rear-mode-control-motor-replacement) ). If the linkage or door stick or bind, repair them as needed.

Rear Mode Control Motor Replacement

SRS components are located in this area. Review the SRS component locations (see COMPONENT LOCATION INDEX ) and the precautions and procedures (see PRECAUTIONS AND PROCEDURES ) before doing repairs or service.

Scheme 245

Scheme 245: Rear Mode Control Motor Replacement
Scheme 245: Rear Mode Control Motor Replacement
  1. Remove the center console (see «CENTER CONSOLE REMOVAL/INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exteriorinterior-trim/#consoles__center-console-removalinstallation) ).
  2. Disconnect the 7P connector (A) from the rear mode control motor (B). Remove the rod (C) of the rear mode control motor from the rear mode control linkage (D). Remove the self-tapping screws and the rear mode control motor from the rear HVAC unit.
  3. Install the motor in the reverse order of removal. Make sure the pin on the motor is properly engaged with the linkage. After installation, make sure the motor runs smoothly.

SRS components are located in this area. Review the SRS component locations (see COMPONENT LOCATION INDEX ) and the precautions and procedures (see PRECAUTIONS AND PROCEDURES ) before doing repairs or service.

Scheme 246

Scheme 246: Rear Climate Control Panel Removal/Installation
Scheme 246: Rear Climate Control Panel Removal/Installation
  1. Remove the HVAC trim (see «CENTER CONSOLE REAR TRIM REMOVAL/ INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exteriorinterior-trim/#consoles__center-console-rear-trim-removal-installation) ).
  2. Remove the self-tapping screws and the rear climate control panel (A).
  3. Install the control panel in the reverse order of removal. After installation, operate the various functions to see whether works properly.
  4. Run the self-diagnostic function to confirm that there are no problems in the system (see «HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITHOUT THE HDS»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#climate-control-system__how-to-use-the-self-diagnostic-function) ).

Rear Blower Motor Replacement

SRS components are located in this area. Review the SRS component locations (see COMPONENT LOCATION INDEX ) and the precautions and procedures (see PRECAUTIONS AND PROCEDURES ) before doing repairs or service.

Scheme 247

Scheme 247: Rear Blower Motor Replacement
Scheme 247: Rear Blower Motor Replacement
  1. Remove the center console (see «CENTER CONSOLE REMOVAL/INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exteriorinterior-trim/#consoles__center-console-removalinstallation) ).
  2. Disconnect the 2P connector (A) from the rear blower motor (B), then remove the wire harness clips (C). Remove the self-tapping screws and the rear blower motor from the rear HVAC unit.
  3. Install the motor in the reverse order of removal.

Rear Heater Core Replacement

SRS components are located in this area. Review the SRS component locations (see COMPONENT LOCATION INDEX ) and the precautions and procedures (see PRECAUTIONS AND PROCEDURES ) before doing repairs or service.

Scheme 248

Scheme 248: Rear Heater Core Replacement
Scheme 248: Rear Heater Core Replacement

Scheme 249

Scheme 249
Scheme 249
  1. When the engine is cool, drain the engine coolant from the radiator (see «COOLANT CHECK»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ).
  2. Remove the center console (see «CENTER CONSOLE REMOVAL/INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exteriorinterior-trim/#consoles__center-console-removalinstallation) ).
  3. Slide the hose clamps (A) back, then disconnect the rear inlet heater hose (B) and the rear outlet heater hose (C) from the rear heater core. Note the orientation of the hose. Engine coolant will run out when the hoses are disconnected; drain it into a clean drip pan. Be sure not to let coolant spill on the electrical parts or the painted surfaces. If any coolant spills, rinse it off immediately.
  4. Turn over the carpet. Remove the self-tapping screws and the clamps (A). Carefully pull out the rear heater core (B) without bending lines.
  5. Install the unit in the reverse order of removal, and note these items: Do not interchange the inlet and outlet heater, hoses, and install the hose clamps securely. Refill the cooling system with engine coolant (see «COOLANT CHECK»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ). Make sure that there is no coolant leakage. Make sure that there is no air leakage.

Rear HVAC Unit Removal/Installation

SRS components are located in this area. Review the SRS component locations (see COMPONENT LOCATION INDEX ) and the precautions and procedures (see PRECAUTIONS AND PROCEDURES ) before doing repairs or service.

Scheme 250

Scheme 250: Rear HVAC Unit Removal/Installation
Scheme 250: Rear HVAC Unit Removal/Installation

Scheme 251

Scheme 251
Scheme 251

Scheme 252

Scheme 252
Scheme 252

Scheme 253

Scheme 253
Scheme 253

Scheme 254

Scheme 254
Scheme 254
  1. When the engine is cool, drain the engine coolant from the radiator (see «COOLANT CHECK»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ).
  2. Recover the refrigerant with a recovery/recycling/ charging station (see «REFRIGERANT RECOVERY»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#climate-control-system__refrigerant-recovery) ).
  3. Remove the center console (see «CENTER CONSOLE REMOVAL/INSTALLATION»(/acura/mdx/ii-2006-2010/remont/exteriorinterior-trim/#consoles__center-console-removalinstallation) ).
  4. Slide the hose clamps (A) back, then disconnect the rear inlet heater hose (B) and the rear outlet heater hose (C) from the rear heater core. Note the orientation of the hose. Engine coolant will run out when the hoses are disconnected; drain it into a clean drip pan. Be sure not to let coolant spill on the electrical parts or the painted surfaces. If any coolant spills, rinse it off immediately.
  5. Turn over the carpet. Remove the bolt, then disconnect the rear suction/receiver lines (A).
  6. Remove the harness clips (A).
  7. Disconnect the connectors (A) from the rear mode control motor, the rear air mix control motor, rear evaporator temperature sensor, rear power transistor, and rear blower motor, then remove the harness clips (B) and connector clip (C).
  8. Remove the mounting bolts and rear HVAC unit (A). Plug or cap the lines immediately after disconnecting them to avoid moisture and dust contamination.
  9. Install the rear heater core, and the rear evaporator core in the reverse order of removal.
  10. Install the unit in the reverse order of removal, and note these items: Do not interchange the inlet and outlet heater hoses, and install the hose clamps securely. Refill the cooling system with engine coolant (see «COOLANT CHECK»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ). Make sure that there is no coolant leakage. Make sure that there is no air leakage. If you're installing a new rear evaporator, add refrigerant oil (DENSO ND-OIL 8) (see «A/C SERVICE TIPS AND PRECAUTIONS»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#climate-control-system__ac-service-tips-and-precautions) ). Replace the O-rings with new ones at each fitting, and apply a thin coat of refrigerant oil before installing them. Be sure to use the correct O-rings for HFC-134a (R-134a) to avoid leakage. Immediately after using the oil, replace the cap on the container, and seal it to avoid moisture absorption. Do not spill the refrigerant oil on the vehicle; it may damage the paint; If the refrigerant oil contacts the paint, wash it off immediately. Charge the system (see «SYSTEM CHARGING»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#climate-control-system__system-charging) ).

Rear HVAC Unit Component Replacement

SRS components are located in this area. Review the SRS component locations (see COMPONENT LOCATION INDEX ) and the precautions and procedures (see PRECAUTIONS AND PROCEDURES ) before doing repairs or service.

Note. The rear blower motor (A), the rear heater core (B), the rear evaporator sensor (C), the rear power transistor (D), the rear air mix control motor (E), the rear mode control motor (F), and the rear expansion valve (G) can be replaced without removing the rear HVAC unit.

Scheme 255

Scheme 255: Rear HVAC Unit Component Replacement
Scheme 255: Rear HVAC Unit Component Replacement
  1. Remove the self-tapping screw and the rear evaporator sensor. Remove the self-tapping screw and the clamp (H), then remove the bolts and the rear evaporator lines (I) with the rear expansion valve. If necessary, remove the rear expansion valve. Use a second wrench to hold the other fitting on the valve so the rear evaporator lines won't twist. Leave the first fitting loosely connected so you can use it to hold the valve while you loosen the second fitting.
  2. If necessary, remove the rear blower motor (see «REAR BLOWER MOTOR REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#rear-climate-control__rear-blower-motor-replacement) ), the rear heater core (see «REAR HEATER CORE REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#rear-climate-control__rear-heater-core-replacement) ), the rear power transistor, the rear air mix control motor (see «REAR AIR MIX CONTROL MOTOR TEST»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#rear-climate-control__rear-air-mix-control-motor-test) ), and the rear mode control motor (see «REAR MODE CONTROL MOTOR TEST»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#rear-climate-control__rear-mode-control-motor-test) ).
  3. Remove the self-tapping screws, and carefully separate the left housing (J) from the right housing (K). Remove the rear evaporator core (U and plate (M).
  4. Reassemble the unit in the reverse order of disassembly, and note these items; Replace all O-rings with new ones at each fitting and apply a thin coat of refrigerant oil before installing them. Be sure to use the correct O-rings for HFC-134a (R-134a) to avoid leakage. Immediately after using the oil, reinstall the cap on the container, and seal it to avoid moisture absorption. Make sure no air is leaking from the left upper housing and the right upper housing fitting and from the upper housings and the lower housing fitting. Install the capillary tube (N) directly against the outlet line, and wrap it with electrical tape (O). Before reassembly, make sure that the rear air mix control linkage and door move smoothly without binding. Before reassembly, make sure that the rear mode control linkage and door move smoothly without binding. After reassembly, make sure the rear air mix control motor runs smoothly (see «REAR AIR MIX CONTROL MOTOR TEST»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#rear-climate-control__rear-air-mix-control-motor-test) ). After reassembly, make sure the rear mode control motor runs smoothly (see «REAR MODE CONTROL MOTOR TEST»(/acura/mdx/ii-2006-2010/remont/automatic-hvac-system/#rear-climate-control__rear-mode-control-motor-test) ). Make sure that there is no coolant leakage.

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