HVAC Systems - Manual Buick Rendezvous I

Fastener Tightening Specifications

Fastener Tightening Specifications

Sensor Resistance Table

Sensor Resistance Table

Scheme 1

Scheme 2

Scheme 3

Scheme 4

Scheme 5

Scheme 6

Scheme 7

Scheme 8

Scheme 9

Scheme 10

HVAC Connector End Views

A/C Compressor Clutch Connector End Connector Part Information 15326801 2-Way F GT 150 Series (LT GRY) Pin Wire Color Circuit No. Function A DK GRN 59 A/C Compressor Clutch Supply Voltage B BLK 1050 Ground

A/C Refrigerant Pressure Sensor Connector End Connector Part Information 12110192 3-Way F Metri-Pack 150 Series (BLK) Pin Wire Color Circuit No. Function A BLK 2751 Low Reference B GRY 2700 5-Volt Reference C RED/BLK 380 A/C Refrigerant Pressure Sensor Signal

Air Temperature Actuator Connector End - Left Connector Part Information 12064978 6-Way F Micro-Pack 100 Series (GRY) Pin Wire Color Circuit No. Function 1-2 - - Not Used 3 BLK 150 Ground 4 DK BLU 1199 Left Air Temperature Door Control 5 - - Not Used 6 BRN 241 Ignition 3 Voltage

Air Temperature Actuator Connector End - Right - CJ3 Connector Part Information 12064993 6-Way F Micro-Pack 100 Series (BLK) Pin Wire Color Circuit No. Function 5-6 - - Not Used 7 BLK 150 Ground 8 WHT/BLK 1236 Right Air Temperature Door Control 9 - - Not Used 10 BRN 241 Ignition 3 Voltage

Blower Motor Connector End Connector Part Information 12084957 2-Way F Metri-Pack 280 Series (BLK) Pin Wire Color Circuit No. Function A RED - Blower Motor Supply Voltage B BLK - Ground

Blower Motor Resistor Assembly Connector End Connector Part Information 12052854 7-Way F Metri-Pack 280 Series (BLK) Pin Wire Color Circuit No. Function A TAN 63 Medium 1 Blower Motor Control B YEL 60 Low Blower Motor Control C PPL 73 Medium 3 Blower Motor Control D LT BLU 72 Medium 2 Blower Motor Control E BLK 150 Ground F ORN 52 High Blower Motor Control G RED 442 Battery Positive Voltage

Evaporator Temperature Sensor Connector End Connector Part Information 12052832 2-Way F Metri-Pack 150 Series (BLK) Pin Wire Color Circuit No. Function A WHT 2622 Evaporator Temperature Sensor Signal B BLK 552 Low Reference

HVAC Control Module Connector End - C1 Connector Part Information 12084994 16-Way F Micro-Pack 100 Series (BLK) Pin Wire Color Circuit No. Function A1 ORN 640 Battery Positive Voltage A2 BRN 241 Ignition 3 Voltage A3 BRN 9 Park Lamp Supply Voltage A4 WHT 193 Rear Defog Relay Control A5 TAN/BLK 2274 Recirculation Door Control A6 DK GRN/ WHT 762 A/C Request Signal A7 TAN 2273 Mode Door Control A8 DK BLU 1199 Left Air Temperature Door Control B1 BLK 150 Ground B2 BLK 552 Low Reference B3 WHT 2622 Evaporator Temperature Sensor Signal B4 GRY 8 Instrument Panel Lamp Supply Voltage B5 DK GRN 71 Off Blower Motor Control B6 WHT/BLK 1236 Right Air Temperature Door Control B7-B8 - - Not Used

HVAC Control Module Connector End - C2 Connector Part Information 12064998 8-Way F Metri-Pack 280 Series (BLK) Pin Wire Color Circuit No. Function A DK GRN 71 OFF Blower Motor Control B BRN 41 Ignition 3 Voltage C ORN 52 High Blower Motor Control D - - Not Used E PPL 73 Medium 3 Blower Motor Control F LT BLU 72 Medium 2 Blower Motor Control G TAN 63 Medium 1 Blower Motor Control H YEL 60 Low Blower Motor Control

Mode Actuator Connector End Connector Part Information 12064993 6-Way F Micro-Pack 100 Series (BLK) Pin Wire Color Circuit No. Function 5-6 - - Not Used 7 BLK 150 Ground 8 TAN 2273 Mode Door Control 9 - - Not Used 10 BRN 241 Ignition 3 Voltage

Recirculation Actuator Connector End Connector Part Information 12064993 6-Way F Micro-Pack 100 Series (BLK) Pin Wire Color Circuit No. Function 5 BRN 241 Ignition 3 Voltage 6 TAN/BLK 2274 Recirculation Door Control 7 BLK 150 Ground 8-10 - - Not Used

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. 3: Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
2. 4: Determine if the Powertrain Control Module has set DTCs which may affect HVAC operation are present.
3. 5: The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.

Diagnostic System Check - HVAC Systems - Manual

Scan Tool Output Controls

PCM Scan Tool Output Controls

Scan Tool Data List

BCM Scan Tool Data List

PCM Scan Tool Data List

Diagnostic Trouble Code (DTC) List

Diagnostic Trouble Code (DTC) List

Circuit Description

The powertrain control module (PCM) monitors the high side refrigerant pressure via a A/C refrigerant pressure sensor. When the pressure is high the signal voltage is high. When the pressure is low the signal voltage is low. When pressure is high the PCM commands the cooling fans on. When pressure is too high or too low the PCM will not allow the A/C compressor clutch to engage.

Conditions for Running the DTC

1. The engine is running.
2. A/C has been requested.

Conditions for Setting the DTC

1. The PCM detects the signal circuit is less than 5 counts (0.09 volt) or more than 250 counts (4.90 volts).
2. The condition exists for 20 seconds.

Action Taken When the DTC Sets

1. The PCM will not illuminate the Malfunction Indicator Lamp (MIL).
2. The PCM stores the failure records.
3. The A/C compressor clutch is disabled.

Conditions for Clearing the DTC

1. The DTC will become history if the PCM no longer detects a failure.
2. The history DTC will clear after 40 fault-free ignition cycles.
3. The DTC can be cleared with a scan tool.

Diagnostic Aids

If the condition is not present refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

The numbers below refer to the step numbers on the diagnostic table

1. 4: If the pressure signal voltage stays high after disconnecting the pressure sensor electrical connector, the signal circuit is shorted to voltage, or the PCM is faulty.
2. 7: Tests for a high resistance or for an open in the ground circuit.
3. 16: This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). Before you replace the PCM, program the new PCM.

DTC P0530

Ignition voltage is supplied directly to the A/C compressor clutch relay. The powertrain control module (PCM) controls the relay by grounding the control circuit of the A/C clutch relay through an internal solid state device. This device is called a driver. The driver supplies the ground for the component that is being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM commands a component ON, the voltage of the control circuit should be near 0 volts. When the PCM commands the control circuit to a component OFF, the voltage potential of the circuit should be near battery voltage. If the fault detection circuit senses an unexpected voltage, this DTC will set.

The PCM will monitor the control circuit to the A/C clutch relay for the following conditions

1. A short to ground
2. A short to voltage
3. An open circuit
4. An open relay coil
5. A relay coil that is shorted internally or which has a very low resistance

If the PCM detects any of these malfunctions, this DTC is set, and the affected driver is disabled.

The ignition voltage is between 9-18 volts.

1. A short to ground, an open circuit, or a short to battery voltage is detected on the control circuit to the A/C clutch relay.
2. The condition is present for at least 30 seconds.

1. The PCM will not illuminate the malfunction indicator lamp (MIL).
2. The PCM will store those conditions which were present when the DTC set. These conditions are recorded as Failure Records data only. This information will not be stored as Freeze Frame data.

1. A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
2. The DTC can be cleared by using a scan tool.

If DTC P0645 cannot be duplicated, review the Failure Records. Observe the vehicle mileage since the diagnostic test last failed. This may help to determine how often the condition which caused the DTC to set occurs. This may assist in diagnosing the condition.

If the condition is intermittent, refer to Testing for Intermittent Conditions and Poor Connections .

The numbers below refer to the step numbers on the diagnostic table

1. 2: Listen for an audible click when the relay operates. Command the ON and the OFF states. Repeat the commands as necessary.
2. 12: The PCM utilizes Electrically Erasable Programmable Read Only Memory (EEPROM). Program the new PCM before you replace the PCM.

DTC P0645

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the HVAC System. Refer to «Checking Aftermarket Accessories»(/buick/rendezvous/i-2001-2007/remont/body-electrical/#wiring-systems-diagnostic-information-and-procedures__checking-aftermarket-accessories) in Wiring Systems.
2. Inspect the system components which are easily accessible or visible for obvious damage or for conditions which could cause the symptom.
3. Verify the A/C compressor clutch turns freely and is not seized.
4. The A/C compressor will not operate in cold, outside air temperatures. Refer to «Air Temperature Description and Operation»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual__air-temperature-description-and-operation) .
5. The following conditions may cause window fogging: A wet carpet High humidity An interior water leak A blocked drain tube to the A/C evaporator Maximum passenger capacity Blocked body pressure relief valves
6. Inspect the air distribution system for causes of reduced airflow: An obstructed or dirty passenger compartment air filter Blocked or damaged air vents

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Symptom List

Refer to one of the following symptom diagnostic procedures

1. «HVAC Compressor Clutch Does Not Engage»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual)
2. «HVAC Compressor Clutch Does Not Disengage»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual__hvac-compressor-clutch-does-not-disengage)
3. «Blower Motor Always On»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual)
4. «Blower Motor Inoperative»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual__blower-motor-inoperative)
5. «Blower Motor Malfunction»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual__blower-motor-malfunction)
6. «Too Hot in Vehicle»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual)
7. «Too Cold in Vehicle»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual)
8. «Air Delivery Improper»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual)
9. «Air Recirculation Malfunction»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual)
10. «Leak Testing»(/buick/rendezvous/i-2001-2007/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__leak-testing) in Heating, Ventilation and Air Conditioning
11. «Defrosting Insufficient»(/buick/rendezvous/i-2001-2007/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__defrosting-insufficient) in Heating, Ventilation and Air Conditioning
12. «Noise Diagnosis - Blower Motor»(/buick/rendezvous/i-2001-2007/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__noise-diagnosis-blower-motor) in Heating, Ventilation and Air Conditioning
13. «Noise Diagnosis - Air Conditioning (A/C) System»(/buick/rendezvous/i-2001-2007/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__noise-diagnosis-air-conditioning-ac) in Heating, Ventilation and Air Conditioning
14. «Noise Diagnosis - HVAC Module»(/buick/rendezvous/i-2001-2007/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__noise-diagnosis-hvac-module) in Heating, Ventilation and Air Conditioning
15. «Odor Diagnosis»(/buick/rendezvous/i-2001-2007/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__odor-diagnosis) in Heating, Ventilation and Air Conditioning

The Mitsubishi scroll type air conditioning (A/C) compressor carries an internal thermal cut off switch. The thermal cut off switch normal operation is to open and disable the compressor under extreme load and temperatures above 155°C (311°F). The internal thermal cut off switch is non-serviceable.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: The A/C compressor relay output is disabled if engine coolant temperature is above 121°C (250°F). The engine coolant indicator will illuminate at this temperature.

1. 3: Place the mode switch in any position except OFF, and place the air temperature control switch in a cold setting. Use the bi-level mode for consistent testing of the A/C system operation.
2. 6: The HVAC control module is inoperative if the module does not respond to any operator control requests.
3. 40: The evaporator temperature sensor is replaced as part of the evaporator core.

HVAC Compressor Clutch Does Not Engage

HVAC Compressor Clutch Does Not Disengage

HVAC Compressor Clutch Does Not Disengage

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step checks for continuous operation of the blower motor.
2. 3: This step tests for a short to voltage in the blower motor control circuits.

Blower Motor Always On

Blower Motor Inoperative

Blower Motor Inoperative

Blower Motor Malfunction

Blower Motor Malfunction

The Mitsubishi scroll type A/C compressor carries an internal thermal cut off switch. The thermal cut off switch normal operation is to open and disable the compressor under extreme load and temperatures above 155°C (311°F). The internal thermal cut off switch is non-serviceable.

The number below refers to the step number on the diagnostic table.

1. 12: The voltage will vary between 0-12 volts during normal operation. The HVAC control module connector must be connected during this step.

Too Hot in Vehicle

The number below refers to the step number on the diagnostic table.

1. 12: The voltage will vary between 0-12 volts during normal operation. The HVAC control module connector must be connected during this step.

Too Cold in Vehicle

The numbers below refer to the step numbers on the diagnostic table.

1. 12: The measured voltage should be near the specified values for each mode position.

1. 14: Two ignition 3 voltage circuits supply the HVAC control module. Test the ignition 3 voltage circuit that does not supply the blower motor switch.

Air Delivery Improper

The number below refers to the step number on the diagnostic table.

1. 9: The HVAC control module is supplied by 2 ignition-3 voltage circuits. Test the ignition-3 voltage circuit that does not supply the blower motor switch.

Air Recirculation Malfunction

Re-Calibrating Actuators

Use the following steps to perform the calibration update

1. Turn OFF the ignition.
2. Remove the battery positive voltage circuit fuse of the HVAC Control Module.
3. Wait 60 seconds.
4. Install the fuse.

Removal Procedure

1. Remove the I/P cluster trim plate bezel. Refer to «Trim Plate Bezel Replacement - Instrument Panel (I/P) Cluster (Aztek)»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) or «Trim Plate Bezel Replacement - Instrument Panel (I/P) Cluster (Rendezvous)»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
2. Remove the HVAC control module retaining screws.
3. Pull the HVAC control module straight out from the I/P.
4. Disconnect the HVAC control module electrical connector.

Installation Procedure

1. Connect the HVAC control module electrical connector.
2. Install the HVAC control module into the I/P opening.
3. Install the HVAC control module retaining screws. Tighten: Tighten the screws to 2.5 N.m (22 lb in).
4. Install the IP cluster trim plate bezel. Refer to «Trim Plate Bezel Replacement - Instrument Panel (I/P) Cluster (Aztek)»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) or «Trim Plate Bezel Replacement - Instrument Panel (I/P) Cluster (Rendezvous)»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages, and Console.
5. Start and allow the engine to run for a least one minute.

1. Remove the I/P accessory trim plate. Refer to «Trim Plate Replacement - Instrument Panel (I/P) Accessory (Aztek)»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
2. Remove the HVAC control module retaining screws.
3. Pull the HVAC control module straight out from the I/P.
4. Disconnect the HVAC control module electrical connectors.

1. Connect the HVAC control module electrical connectors.
2. Push the HVAC control module into I/P opening.
3. Install the HVAC control module retaining screws. Tighten: Tighten the screws to 2.5 N.m (22 lb in).
4. Install the I/P accessory trim plate. Refer to «Trim Plate Replacement - Instrument Panel (I/P) Accessory (Aztek)»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages, and Console.
5. Start and allow the engine to run for a least one minute.

1. Remove the knee bolster. Refer to «Knee Bolster Replacement»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
2. Set the HVAC controls to the vent mode to position the defroster door lever.
3. Remove the temperature door lever bolt (3) from the HVAC module.
4. Disconnect and remove the temperature door lever spring (2).
5. Disconnect and remove the temperature door lever (1) from the temperature door.
6. Disconnect the air temperature actuator electrical connector.
7. Remove the air temperature actuator mounting screws.
8. Remove the air temperature actuator.

1. Install the air temperature actuator.
2. Install the air temperature actuator mounting screws. Tighten: Tighten the screws to 1.6 N.m (14 lb in).
3. Connect the air temperature actuator electrical connector.
4. Install the temperature door lever (1) to the temperature door.
5. Connect the temperature door lever spring (2) to the temperature door lever (1) and HVAC module case.
6. Install the temperature door lever bolt (3) to the HVAC module case. Tighten: Tighten the bolt to 0.9 N.m (8 lb in).
7. Install the knee bolster. Refer to «Knee Bolster Replacement»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
8. Recalibrate the actuators. Refer to «Re-Calibrating Actuators»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual__re-calibrating-actuators) .

1. Remove the instrument panel (I/P) compartment. Refer to «Compartment Replacement - Instrument Panel (I/P)»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
2. Disconnect and remove the right hand temperature door lever spring (2).
3. Disconnect and remove the right hand temperature lever (1) from the right hand temperature door.
4. Disconnect the right hand temperature actuator electrical connector.
5. Remove the right hand temperature actuator mounting screws.
6. Remove the right hand temperature actuator.

1. Install the right hand temperature actuator.
2. Install the right hand temperature actuator mounting screws. Tighten: Tighten the screws to 1.6 N.m (14 lb in).
3. Connect the right hand temperature actuator electrical connector.
4. Install the right hand temperature lever (1) to the right hand temperature door.
5. Connect the right hand temperature door lever spring (2) to the right hand temperature door lever (1) and HVAC module case.
6. Install the I/P compartment. Refer to «Compartment Replacement - Instrument Panel (I/P)»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
7. Recalibrate the actuators. Refer to «Re-Calibrating Actuators»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual__re-calibrating-actuators) .

1. Remove the knee bolster. Refer to «Knee Bolster Replacement»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
2. Set the HVAC controls to the vent mode to position the defroster door lever.
3. Remove the left hand temperature door lever bolt (3) from the HVAC module.
4. Disconnect and remove the left hand temperature door lever spring (2).
5. Disconnect and remove the left hand temperature door lever (1) from the left hand temperature door.
6. Disconnect the left hand air temperature actuator electrical connector.
7. Remove the left hand air temperature actuator mounting screws.
8. Remove the left hand air temperature actuator.

1. Install the left hand air temperature actuator.
2. Install the left hand air temperature actuator mounting screws. Tighten: Tighten the screws to 1.6 N.m (14 lb in).
3. Connect the left hand air temperature actuator electrical connector.
4. Install the left hand temperature door lever (1) to the left hand temperature door.
5. Connect the left hand temperature door lever spring (2) to the left hand temperature door lever (1) and HVAC module case.
6. Install the left hand temperature door lever bolt (3) to the HVAC module case. Tighten: Tighten the bolt to 0.9 N.m (8 lb in).
7. Install the knee bolster. Refer to «Knee Bolster Replacement»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
8. Recalibrate the actuators. Refer to «Re-Calibrating Actuators»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual__re-calibrating-actuators) .

1. Remove the knee bolster from the instrument panel. Refer to «Knee Bolster Replacement»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
2. Disconnect the I/P wiring harness clip from the I/P support bracket.
3. Disconnect the mode actuator electrical connector.
4. Open the mode actuator push rod retainer clip (1) with a small flat-bladed screwdriver.
5. Disconnect the mode actuator push rod (2) from the retainer clip (1).
6. Remove the mode actuator mounting screws.
7. Remove the mode door actuator.

1. Install the mode actuator.
2. Install the mode actuator mounting screws. Tighten: Tighten the screws to 1.6 N.m (14 lb in).
3. Connect the mode actuator push rod (2) to the retainer clip (1).
4. Close the push rod retainer clip (1).
5. Connect the mode actuator electrical connector.
6. Connect the I/P wiring harness clip to the I/P support bracket.
7. Install the knee bolster. Refer to «Knee Bolster Replacement»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
8. Recalibrate the actuators. Refer to «Re-Calibrating Actuators»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual__re-calibrating-actuators) .

1. Remove the upper I/P trim pad. Refer to «Trim Pad Replacement - Instrument Panel (I/P) Upper (Aztek)»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) or «Trim Pad Replacement - Instrument Panel (I/P) Upper (Rendezvous)»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
2. Disconnect the recirculation actuator electrical connector.
3. Remove the mounting screws from the recirculation actuator.
4. Remove the recirculation actuator.

1. Install the recirculation actuator.
2. Install the recirculation actuator mounting screws. Tighten: Tighten the screws to 1.6 N.m (14 lb in).
3. Connect the recirculation actuator electrical connector.
4. Install the upper I/P trim pad. Refer to «Compartment Replacement - Instrument Panel (I/P)»(/buick/rendezvous/i-2001-2007/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
5. Recalibrate the actuators. Refer to «Re-Calibrating Actuators»(/buick/rendezvous/i-2001-2007/remont/manual-hvac-system/#hvac-systems-manual__re-calibrating-actuators) .

Air Delivery Description and Operation

The air delivery description and operation is divided into four areas

1. HVAC Control Components
2. Air Speed
3. Air Delivery
4. Recirculation Operation

HVAC Control Module

The HVAC control module is a non-class 2 device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The ignition 3 and battery positive voltage circuits provide power to the control module. The control module supports the following features

Air Delivery Description and Operation

Mode Actuator

The mode actuator is a 3 wire bi-directional electric motor. Ignition 3 voltage, ground and control circuits enable the actuator to operate. The control circuit uses a 0-12 volt linear-ramped signal to command the actuator movement. The 0 and 12 volt control values represent the opposite limits of the actuator range of motion. The values in between 0 and 12 volts correspond to the positions between the limits. When the HVAC control module sets a commanded, or targeted, value, the control signal is set to a value between 0-12 volts. The actuator shaft rotates until the commanded position is reached. The module will maintain the control value until a new commanded value is needed.

Recirculation Actuator

The recirculation actuator is a 3 wire bi-directional electric motor. Ignition 3 voltage, ground and control circuits enable the actuator to operate. The control circuit is either grounded or opened during normal operation. If the control circuit is grounded, then the shaft rotates in the opposite direction than it would if the circuit was opened. The actuator shaft rotates until the limit is reached. If the module needs to reverse the direction of rotation, then the control circuit's state is reversed. The open circuits are held at ignition 3 voltage from the actuator. The module will maintain the control circuit's state until a new position is needed.

Air Speed

The HVAC control assembly applies voltage to the blower motor control circuit that corresponds to the selected blower speed. The resistors and the blower motor are in a series circuit. The following list represents the number of resistors in series with the blower motor per particular speed request

1. Low speed-4 resistors
2. Medium 1 speed-3 resistors
3. Medium 2 speed-2 resistors
4. Medium 3 speed-1 resistor

When the operator requests High speed, the HVAC control assembly applies voltage to the blower motor relay through the high blower motor control circuit. The voltage energizes the blower motor relay, connecting the blower motor to battery positive voltage.

Off Mode

When the OFF position is selected, the HVAC control module applies voltage to the blower switch off input within the HVAC control module through the off blower motor control circuit. When the HVAC control module receives this input, any A/C request will be cancelled and the A/C request LED will turn off. Fresh air will still be brought in from the outside, but the LED indicator will not illuminate.

Air Delivery

The HVAC control module controls the mode actuator in order to distribute airflow to a desired outlet. When the mode door is moved to the defrost position, the A/C compressor clutch engages and the recirculation actuator will be moved to the outside air position. Regardless of the mode setting, a small amount of air will be diverted to the defrost ducts to reduce windshield fogging. When the mode actuator sees an open in the control circuit, the actuator defaults to 6 volts and positions the mode door to the floor position. On startup, the HVAC control module will place the mode door in the last selected position.

Recirculation Operation

The HVAC control module controls the air intake through the recirculation actuator. Recirculation is only available when the HVAC control module is in Vent or Bi-level. The operator must activate the blower for Recirculation operation. When the recirculation actuator sees an open in the control circuit, the actuator will default to the recirculation position.

Air Temperature Description and Operation

The four primary areas of air controls are

1. HVAC Control Components
2. Heating and A/C Operation
3. Engine Coolant
4. A/C Cycle

The HVAC control module is a non-class 2 device that interfaces between the operator and the HVAC System to maintain air temperature and distribution settings. The ignition 3 and battery positive voltage circuits provide power to the control module. The control module supports the following features

Air Temperature Description and Operation

Air Temperature Actuator

The air temperature actuator is a 3 wire bi-directional electric motor. Ignition 3-voltage, ground and control circuits enable the actuator to operate. The control circuit uses a 0-12 volt linear-ramped signal to command the actuator movement. The 0 and 12-volt control values represent the opposite limits of the actuator range of motion. The values in between 0 and 12 volts correspond to the positions between the limits.

When the HVAC control module sets a commanded, or targeted, value, the control signal sets to a value between 0-12 volts. Actuator shaft rotation is the results of a commanded position input by the vehicle operator. With a new actuator commanded value action, the maintained actuator control value is changed.

A/C Refrigerant Pressure Sensor

The A/C refrigerant pressure sensor is a 3-wire piezoelectric pressure transducer. A 5-volt reference, low reference, and signal circuits enable the sensor to operate. The A/C pressure signal can be between 0-5 volts. When the A/C refrigerant pressure is low, the signal value is near 0 volts. When the A/C refrigerant pressure is high, the signal value is near 5 volts.

The A/C refrigerant pressure sensor protects the A/C system from operating when an excessively high or low pressure condition exists. The powertrain control module (PCM) disables the compressor clutch under the following conditions

1. A/C pressure is more than 2979 kPa (432 psi). The clutch will be enabled after the pressure decreases to less than 1510 kPa (219 psi).
2. A/C pressure is less than 186 kPa (27 psi). The clutch will be enabled after the pressure increases to more than 207 kPa (30 psi).

Evaporator Temperature Sensor

The evaporator temperature sensor protects the A/C system. The sensor located on the evaporator core provides the HVAC control module with the surface temperature of the evaporator core. If the evaporator temperature sensor reads a temperature of 0°C (32°F), the HVAC control module will turn off the A/C compressor clutch until evaporator temperatures reach 2°C (36°F).

Heating and A/C Operation

The purpose of the heating and A/C System is to provide heated and cooled air to the interior of the vehicle. The A/C System will also remove humidity from the interior and reduce windshield fogging. The vehicle operator can determine the passenger compartment temperature by adjusting the air temperature switch. Regardless of the temperature setting, the following can effect the rate that the HVAC system can achieve the desired temperature

1. Recirculation actuator setting
2. Difference between inside and desired temperature
3. Difference between ambient and desired temperature
4. Blower motor speed setting
5. Mode setting

The control module takes the following actions when a mode operation is selected, and an air temperature setting is selected

1. When the air temperature switch is placed in the warmest position, the control module commands the air temperature door to divert maximum air past the heater core.
2. When the air temperature switch is placed in the coldest position, the control module commands the air temperature door to direct air to bypass the heater core.

The A/C system can be engaged by pressing the A/C switch. The A/C switch will illuminate when the A/C switch is pressed to the on position. The control module sends an A/C request message to the body control module (BCM) which sends a class 2 message to the powertrain control module (PCM). The HVAC System uses a scroll compressor that incorporates a thermal switch that opens once the compressor temperature is more than 155°C (311°F). The following conditions must be met in order for the PCM to turn on the compressor clutch

1. HVAC control module Ambient temperature more than 2°C (36°F) Evaporator Temperature more than 2°C (36°F)
2. BCM Battery voltage between 9 - 16 volts A/C request from the HVAC control module
3. PCM Engine coolant temperature (ECT) is less than 125°C (257°F) Engine RPM is below 5,000 RPM A/C Pressure is between 1510 - 2979 kPa (219 - 432 psi)

Once engaged, the compressor clutch will be disengaged for the following conditions

1. Compressor thermal switch is opened
2. Throttle position is 100%
3. A/C Pressure is more than 2979 kPa (432 psi)
4. A/C Pressure is less than 1510 kPa (219 psi)
5. Engine coolant temperature (ECT) is more than 125°C (257°F)
6. Engine speed is more than 5,500 RPM
7. Transmission shift
8. PCM detects excessive torque load
9. PCM detects insufficient idle quality
10. PCM detects a hard launch condition

When the compressor clutch disengages, the compressor clutch diode protects the electrical system from a voltage spike.

Engine Coolant

Engine coolant is the important element of the heating system. The thermostat controls the normal engine operating coolant temperature. The thermostat also creates a restriction for the cooling system that promotes a positive coolant flow and helps prevent cavitation.

Coolant enters the heater core through the inlet heater hose, in a pressurized state. The heater core is located inside the HVAC module. The ambient air drawn through the HVAC module absorbs the heat of the coolant flowing through the heater core. Heated air distribution to the passenger compartment, through the HVAC module maintains passenger comfort. Opening or closing the HVAC module temperature door controls heat delivered to the passenger compartment. The coolant exits the heater core through the return heater hose and recirculates back through the engine cooling system.

A/C Cycle

Refrigerant is the key element in an air conditioning system. R-134a is presently the only EPA approved refrigerant for automotive use. R-134a is a very low temperature gas that can transfer the undesirable heat and moisture from the passenger compartment to the outside air.

A Mitsubishi scroll compressor is used on this model year vehicle. The A/C compressor is belt driven and operates when the magnetic clutch is engaged. The compressor builds pressure on the vapor refrigerant. Compressing the refrigerant also adds heat to the refrigerant. The refrigerant is discharged from the compressor, through the discharge hose, and forced to flow to the condenser and then through the balance of the A/C system. The A/C system is mechanically protected with the use of a high pressure relief valve. If the high pressure switch were to fail or if the refrigerant system becomes restricted and refrigerant pressure continued to rise, the high pressure relief will pop open and release refrigerant from the system.

Compressed refrigerant enters the condenser in a high temperature, high pressure vapor state. As the refrigerant flows through the condenser, the heat of the refrigerant is transferred to the ambient air passing through the condenser. Cooling the refrigerant causes the refrigerant to condense and change from a vapor to a liquid state.

The condenser is located in front of the radiator for maximum heat transfer. The condenser is made of aluminum tubing and aluminum cooling fins, which allows rapid heat transfer for the refrigerant. The semi-cooled liquid refrigerant exits the condenser and flows through the liquid line, to the TXV.

The TXV is located at the evaporator inlet. The TXV is the dividing point for the high and the low pressure sides of the A/C system. As the refrigerant passes through the TXV, the pressure on the refrigerant is lowered. Due to the pressure differential on the liquid refrigerant, the refrigerant will begin to boil at the TXV. The TXV also meters the amount of liquid refrigerant that can flow into the evaporator.

Refrigerant exiting the TXV flows into the evaporator core in a low pressure, liquid state. Ambient air is drawn through the HVAC module and passes through the evaporator core. Warm and moist air will cause the liquid refrigerant boil inside of the evaporator core. The boiling refrigerant absorbs heat from the ambient air and draws moisture onto the evaporator. The refrigerant exits the evaporator through the suction line and back to the compressor, in a vapor state, and completing the A/C cycle of heat removal. At the compressor, the refrigerant is compressed again and the cycle of heat removal is repeated.

The conditioned air is distributed through the HVAC module for passenger comfort. The heat and moisture removed from the passenger compartment will also change form, or condense, and is discharged from the HVAC module as water.

Special Tools

Special Tools Illustration Tool Number/Description J 43600 ACR 2000 Air Conditioning Service 7000081 Tech 2 Kit

Scheme 11

Scheme 12

See also:
• Diagnostic Starting Point - Heating, Ventilation and Air Conditioning
• Scan Tool Does Not Power Up
• Diagnostic Trouble Code (DTC) List
• Testing for Intermittent Conditions and Poor Connections
• Circuit Testing
• Wiring Repairs
• Connector Repairs
• Powertrain Control Module (PCM) Replacement
• Checking Aftermarket Accessories
• Leak Testing
• Defrosting Insufficient
• Noise Diagnosis - Blower Motor
• Noise Diagnosis - Air Conditioning (A/C) System
• Noise Diagnosis - HVAC Module
• Odor Diagnosis
• Engine Coolant Temperature Indicator Always On
• Body Control Module Replacement
• Heating Performance Diagnostic
• Trim Plate Bezel Replacement - Instrument Panel (I/P) Cluster (Aztek)
• Symptoms - HVAC Systems - Manual
• Diagnostic Trouble Code (DTC) List
• HVAC Connector End Views
• HVAC Compressor Clutch Does Not Disengage
• Air Delivery Description and Operation
• Air Temperature Description and Operation
• Blower Motor Inoperative
• Blower Motor Malfunction
• Sensor Resistance Table
• Scan Tool Output Controls
• Re-Calibrating Actuators