Climate Control System

Climate Control System

 WARNING: Take the following precautions when repairing an air conditioning system containing R-134a:

• Always wear safety goggles.
• Avoid contact with liquid refrigerant R-134a. R-134a vaporizes at approximately -25°C (-13°F) under atmospheric pressure and will freeze skin tissue.
• Never allow refrigerant R-134a gas to escape in quantity in an occupied space. It will displace the oxygen needed to support life.
• Never use a torch in an atmosphere containing R-134a gas. R-134a is non-toxic at all normal conditions, but it decomposes when exposed to high temperatures such as a torch flame. During decomposition it releases irritating and toxic gasses (as described in the Material Safety Data Sheet from the manufacturer). Decomposition products are hydrofluoric acid, carbon dioxide and water.

NOTICE: To avoid damaging the vehicle or Air Conditioning (A/C) components, observe the following precautions.

• Identify and analyze the A/C refrigerant of all vehicles prior to refrigerant charging. Failure to do so can contaminate the shop bulk refrigerant and other vehicles.
• Do not add R-12 refrigerant to an A/C system that uses R-134a refrigerant. These 2 types of refrigerants must never be mixed. Doing so can damage the A/C system.
• To prevent refrigerant slugging from damaging the A/C compressor, charge the A/C system with R-134a refrigerant gas while the engine is running only at the low-pressure side.
• Use only R-134a refrigerant. Due to environmental concerns, when the A/C system is evacuated, the refrigerant must be collected using refrigerant recovery/recycling equipment. Federal, State/Provincial and/or local laws REQUIRE that R-134a be recovered into appropriate recovery equipment and the process be conducted by qualified technicians who have been certified by an approved organization, such as ASE or MACS . Use of a recovery machine dedicated to R-134a reduces the possibility of oil and refrigerant incompatibility concerns. Refer to the instructions provided by the equipment manufacturer when removing refrigerant from or charging the A/C system.
• R-134a refrigerant must not be mixed with air for leak testing or used with air for any other purpose above atmospheric pressure. R-134a is combustible when mixed with high concentrations of air and higher pressures.
• A number of manufacturers are producing refrigerant products that are described as direct substitutes for refrigerant R-134a. The use of any unauthorized substitute refrigerant can severely damage the A/C components. If repair is required, use only new or recycled refrigerant R-134a.

NOTICE: To avoid contamination of the Air Conditioning (A/C) system, observe the following precautions.

• Never open or loosen a connection before recovering the refrigerant.
• When loosening a connection, if any residual pressure is evident, allow it to leak out before opening the fitting.
• Evacuate a system that has been opened to install a new component or one that has discharged through leakage before charging.
• Seal open fittings with a cap or plug immediately after disconnecting a component from the system.
• Clean the outside of the fittings thoroughly before disconnecting a component from the system.
• Do not remove the sealing caps from a new component until ready to install.
• Refrigerant oil absorbs moisture from the atmosphere if left uncapped. Do not open an oil container until ready to use and install the cap immediately after using. Store the oil in a clean, moisture-free container.
• Install a new O-ring seal before connecting an open fitting. Coat the fitting and O-ring seal with PAG oil before connecting.
• When installing a refrigerant line, avoid sharp bends. Position the line away from the exhaust or any sharp edges that can chafe the line.
• Tighten threaded fittings only to specifications. The steel and aluminum fittings used in the refrigerant system will not tolerate overtightening.
• When disconnecting a fitting, use a wrench on both halves of the fitting to prevent twisting of the refrigerant lines or tubes.
• Do not open a refrigerant system or uncap a new component unless it is as close as possible to room temperature. This prevents condensation from forming inside a component that is cooler than the surrounding air.

For additional refrigerant system and component information, refer to Section 412-01 .

The system consists of the following components:

• A/C compressor and clutch assembly
• A/C condenser core with integrated receiver/drier on 3.5L Ti-VCT equipped vehicles
• A/C evaporator core
• A/C receiver/drier on 3.5L GTDI equipped vehicles
• A/C pressure transducer
• Connecting refrigerant lines
• TXV
• Heater core and evaporator core housing
• FCIM
• FDIM
• HVAC module
• Temperature blend door actuator(s)
• Defrost/panel/floor mode door actuator
• Air inlet mode door actuator
• Blower motor speed control
• Blower motor
• In-vehicle temperature/humidity sensor
• Autolamp/sunload sensor
• Evaporator temperature sensor
• AAT sensor

EMTC System

System Operation

The EMTC system heats or cools the vehicle depending on the HVAC module control panel selection.

• The control panel selection determines heating or cooling, air distribution and enables blower motor operation.
• The temperature control setting determines the outlet air temperature.
• The blower motor switch varies the blower motor speed.
• During A/C operation, the system reduces the relative humidity of the air inside the vehicle.

Remote Start System Behavior — Message Center Set to Auto

This vehicle is equipped with a remote start feature. In addition to being able to start the vehicle remotely, the remote start feature also uses other vehicle systems to increase the level of comfort to the vehicle occupants upon entering the vehicle. For additional information on the remote start feature and the other vehicle systems it uses, refer to Section 303-06 .

When the remote start feature is used, the climate control system automatically sets certain parameters in an attempt to achieve a comfortable cabin temperature. These parameters are set based on outside air temperature. During remote start, the outside air temperature is continually evaluated and HVAC system operation changes if the outside air changes between cold, moderate and warm temperatures.

For cold ambient air temperatures (below 0°C (32°F)):

• the airflow mode is set to FLOOR/DEFROST if Front Defrost is set to Off in the message center.
• the airflow mode is set to DEFROST if Front Defrost is set to Auto in the message center.
• the temperature is set to full HOT.
• the blower speed is set to HIGH.
• the air inlet mode is set to fresh air.
• A/C is set to OFF.

For moderate ambient air temperatures (between 0°C (32°F) and 27°C (80°F)):

• the airflow mode is set to the last user setting.
• the temperature is set to the last user setting.
• the blower speed is set to the last user setting.
• the air inlet mode is set to the last user setting.
• A/C is set to the last user setting.

For warm ambient air temperatures (above 27°C (80°F)):

• the airflow mode is set to MAX A/C.
• the temperature is set to full COOL.
• the blower speed is set to HIGH.
• the air inlet mode is set to RECIRC.
• A/C is set to ON.

Remote Start System Behavior — Message Center Set to Last User Settings

This vehicle is equipped with a remote start feature. In addition to being able to start the vehicle remotely, the remote start feature also uses other vehicle systems to increase the level of comfort to the vehicle occupants upon entering the vehicle. For additional information on the remote start feature and the other vehicle systems it uses, refer to Section 303-06 .

When the remote start feature is used, the climate control system automatically sets certain parameters in an attempt to achieve a comfortable cabin temperature. These parameters are set based on outside air temperature. During remote start, the outside air temperature is continually evaluated and HVAC system operation changes if the outside air changes between cold, moderate and warm temperatures.

For additional information regarding the message center, refer to Section 413-01 .

When Heater — A/C is set to Last User Settings in the message center, the remote start sets the climate control system to the following settings:

For cold ambient air temperatures as determined by the HVAC module:

• the airflow mode is set to the last user setting if Front Defrost is set to Off in the message center.
• the airflow mode is set to DEFROST if Front Defrost is set to Auto in the message center.
• the temperature is set to the last user setting.
• the blower speed is set to the last user setting.
• the air inlet mode is set to the last user setting.
• A/C is set to the last user setting.

For moderate and warm ambient air temperatures as determined by the HVAC module:

• the airflow mode is set to the last user setting.
• the temperature is set to the last user setting.
• the blower speed is set to the last user setting.
• the air inlet mode is set to the last user setting.
• A/C is set to the last user setting.

System Airflow and Mode Description

Max A/C

When MAX A/C is selected:

• the air inlet door closes, preventing outside air and admitting only recirculated air.
• the RECIRC indicator is illuminated (RECIRC forced on).
• the mode doors direct airflow to the instrument panel A/C registers.
• blended air temperature is available.
• the A/C request button is illuminated.
• the A/C compressor operates if the outside temperature is above approximately 6°C (43°F).
• the blower motor is on.

PANEL

When PANEL is selected:

• the RECIRC request button is enabled. If the RECIRC request button is selected (indicator on), the air inlet door closes, preventing outside air from entering the passenger compartment. If the RECIRC request button is not selected (indicator off), the air inlet door opens, allowing only outside air into the passenger compartment.
• the mode doors direct airflow to the instrument panel A/C registers.
• blended air temperature is available. The airflow temperature can only be cooled below the outside air temperature when A/C compressor operation has been selected by pressing the A/C request button (indicator on).
• the A/C request button is enabled. The A/C compressor operates and the indicator illuminates if the A/C request button is selected and the outside temperature is above approximately 6°C (43°F).
• the blower motor is on.

PANEL/FLOOR

When PANEL/FLOOR is selected:

• the RECIRC request button is enabled. If the RECIRC request button is selected (indicator on), the air inlet door closes, preventing outside air from entering the passenger compartment. If the RECIRC request button is not selected (indicator off), the air inlet door opens, allowing only outside air into the passenger compartment.
• the mode doors direct airflow to the floor duct and the instrument panel A/C registers. A small amount of airflow from the side window demisters and defrost duct is present.
• blended air temperature is available. The airflow temperature can only be cooled below the outside air temperature when A/C compressor operation has been selected by pressing the A/C request button (indicator on).
• the A/C request button is enabled. The A/C compressor operates and the indicator illuminates if the A/C request button is selected and the outside temperature is above approximately 6°C (43°F).
• the blower motor is on.

OFF

When OFF is selected:

• the air inlet door closes, preventing outside air and allowing only recirculated air.
• the blower motor is off.

FLOOR

When FLOOR is selected:

• the RECIRC request button is enabled. If the RECIRC request button is selected (indicator on), the air inlet door closes, preventing outside air from entering the passenger compartment. If the RECIRC request button is not selected (indicator off), the air inlet door opens, allowing only outside air into the passenger compartment.
• the mode doors direct airflow to the floor duct. A small amount of airflow from the defroster duct and side window demisters is present.
• blended air temperature is available. The airflow temperature can only be cooled below the outside air temperature when A/C compressor operation has been selected by pressing the A/C request button (indicator on).
• the A/C request button is enabled. The A/C compressor operates and the indicator illuminates if the A/C request button is selected and the outside temperature is above approximately 6°C (43°F).
• the blower motor is on.

FLOOR/DEFROST

When FLOOR/DEFROST is selected:

• the RECIRC request button is enabled. If the RECIRC request button is selected (indicator on), the air inlet door closes, preventing outside air from entering the passenger compartment. If the RECIRC request button is not selected (indicator off), the air inlet door opens, allowing only outside air into the passenger compartment.
• the mode doors direct airflow to the floor duct, the defroster duct and the side window demisters.
• blended air temperature is available.
• the A/C request button toggles the indicator on and off. To reduce fogging, the A/C compressor operates automatically, regardless of indicator status, if the outside temperature is above approximately 6°C (43°F).
• the blower motor is on.

DEFROST

When DEFROST is selected:

• the RECIRC request button is disabled. The air inlet door opens, allowing only outside air into the passenger compartment.
• the mode doors direct airflow to the defroster duct and side window demisters. A small amount of airflow from the floor duct is present.
• blended air temperature is available.
• the A/C request button toggles the indicator on and off. To reduce fogging, the A/C compressor operates automatically, regardless of indicator status, if the outside temperature is above approximately 6°C (43°F).
• the blower motor is on.

DATC System

System Operation

The DATC system maintains the selected vehicle interior temperature by heating and/or cooling the air.

• During A/C operation, the system reduces the relative humidity of the air inside the vehicle.
• The driver may override the automatic mode of operation.
• The temperature control setting is the desired cabin air temperature.
• The blower motor control override buttons vary the blower motor speed.
• The driver side and passenger side temperature settings can be individually controlled.

When the DATC system is set to AUTO the air distribution direction, blower motor speed, A/C compressor operation and air inlet door mode are automatically controlled based on the temperature(s) selected.

The DATC system manual override settings allow:

• the air distribution direction to be manually selected.
• the blower motor speed to be manually selected.
• recirculation mode to be manually selected in all modes except DEFROST. The A/C request can be manually selected by pressing the A/C request switch.
• A/C compressor operation to be manually selected except in DEFROST and FLOOR/DEFROST.

MyTemp

The MyTemp feature stores and recalls a driver’s preset temperature. This feature is provided so this temperature can be quickly adjusted to a frequently used setting with a single button press. For additional information about MyTemp, refer to the Owner's Literature.

Remote Start System Behavior — Message Center Set to Auto

This vehicle is equipped with a remote start feature. In addition to being able to start the vehicle remotely, the remote start feature also uses other vehicle systems to increase the level of comfort to the vehicle occupants upon entering the vehicle. For additional information on the remote start feature and the other vehicle systems it uses, refer to Section 303-06 .

When the remote start feature is used, the climate control system automatically sets certain parameters in an attempt to achieve a comfortable cabin temperature. These parameters are set based on outside air temperature. During remote start, the outside air temperature is continually evaluated and HVAC system operation changes if the outside air changes between cold, moderate and warm temperatures.

For additional information regarding the message center, refer to Section 413-01 .

When Heater — A/C is set to Auto in the message center, the remote start sets the climate control system to the following settings:

For cold ambient air temperatures as determined by the HVAC module AUTO mode to request heat:

• the airflow mode is set to AUTO if Front Defrost is set to Off in the message center. If the HVAC module requests FLOOR in AUTO mode, the remote start mode uses FLOOR/DEFROST.
• the airflow mode is set to DEFROST if Front Defrost is set to Auto in the message center.
• the temperature is set to 22°C (72°F).
• the blower speed is set to AUTO.
• the air inlet mode is set to AUTO.
• A/C is set to AUTO.

For moderate and warm ambient air temperatures as determined by the HVAC module AUTO mode to request heat or cooling:

• the airflow mode is set to AUTO.
• the temperature is set to 22°C (72°F).
• the blower speed is set to AUTO.
• the air inlet mode is set to AUTO.
• A/C is set to AUTO.

Remote Start System Behavior — Message Center Set to Last User Settings

This vehicle is equipped with a remote start feature. In addition to being able to start the vehicle remotely, the remote start feature also uses other vehicle systems to increase the level of comfort to the vehicle occupants upon entering the vehicle. For additional information on the remote start feature and the other vehicle systems it uses, refer to Section 303-06 .

When the remote start feature is used, the climate control system automatically sets certain parameters in an attempt to achieve a comfortable cabin temperature. These parameters are set based on outside air temperature. During remote start, the outside air temperature is continually evaluated and HVAC system operation changes if the outside air changes between cold, moderate and warm temperatures.

For additional information regarding the message center, refer to Section 413-01 .

When Heater — A/C is set to Last User Settings in the message center, the remote start sets the climate control system to the following settings:

For cold ambient air temperatures as determined by the HVAC module:

• the airflow mode is set to the last user setting if Front Defrost is set to Off in the message center.
• the airflow mode is set to DEFROST if Front Defrost is set to Auto in the message center.
• the temperature is set to the last user setting.
• the blower speed is set to the last user setting.
• the air inlet mode is set to the last user setting.
• A/C is set to the last user setting.

For moderate and warm ambient air temperatures as determined by the HVAC module AUTO mode to request heating or cooling:

• the airflow mode is set to the last user setting.
• the temperature is set to the last user setting.
• the blower speed is set to the last user setting.
• the air inlet mode is set to the last user setting.
• A/C is set to the last user setting.

System Airflow and Mode Description

AUTO

When AUTO is selected:

• the temperature control setting is manually set to the desired setting.
• the air inlet door is automatically controlled by the HVAC module based on the temperature setting.
• the mode door is automatically controlled by the HVAC module based on the temperature setting.
• the temperature blend doors are automatically controlled by the HVAC module based on the temperature setting.
• the A/C compressor is automatically controlled by the HVAC module based on the temperature setting. The A/C compressor will not operate if the outside temperature is below approximately 6°C (43°F).
• the blower motor is on. The blower motor speed is automatically controlled by the HVAC module based on the temperature setting, but can be manually overridden.

OFF

When OFF is selected:

• the air inlet door closes, preventing outside air and allowing only recirculated air.
• the blower motor is off.

Max A/C

When MAX A/C is selected:

• the air inlet door closes, preventing outside air and allowing only recirculated air.
• the RECIRC button is disabled and the indicator is illuminated (RECIRC forced on).
• the mode doors direct airflow to the instrument panel A/C registers.
• blended air temperature is available.
• the A/C request button is illuminated and will be disabled.
• the A/C compressor operates if the outside temperature is above approximately 6°C (43°F).
• the blower motor is on.

PANEL

When PANEL is selected:

• the RECIRC request button is enabled. If the RECIRC request button is selected (indicator on), the air inlet door closes, preventing outside air from entering the passenger compartment. If the RECIRC request button is not selected (indicator off), the air inlet door opens, allowing only outside air into the passenger compartment.
• the mode doors direct airflow to the instrument panel A/C registers.
• blended air temperature is available. The airflow temperature can only be cooled below the outside air temperature when A/C compressor operation has been selected by pressing the A/C request button (indicator on).
• the A/C request button is enabled. The A/C compressor operates and the indicator illuminates if the A/C request button is selected and the outside temperature is above approximately 6°C (43°F).
• the blower motor is on.

PANEL/FLOOR

When PANEL/FLOOR is selected:

• the RECIRC request button is enabled. If the RECIRC request button is selected (indicator on), the air inlet door closes, preventing outside air from entering the passenger compartment. If the RECIRC request button is not selected (indicator off), the air inlet door opens, allowing only outside air into the passenger compartment.
• the mode doors direct airflow to the floor duct and the instrument panel A/C registers. A small amount of airflow from the side window demisters and defrost duct is present.
• blended air temperature is available. The airflow temperature can only be cooled below the outside air temperature when A/C compressor operation has been selected by pressing the A/C request button (indicator on).
• the A/C request button is enabled. The A/C compressor operates and the indicator illuminates if the A/C request button is selected and the outside temperature is above approximately 6°C (43°F).
• the blower motor is on.

FLOOR

When FLOOR is selected:

• the RECIRC request button is enabled. If the RECIRC request button is selected (indicator on), the air inlet door closes, preventing outside air from entering the passenger compartment. If the RECIRC request button is not selected (indicator off), the air inlet door opens, allowing only outside air into the passenger compartment.
• the mode doors direct airflow to the floor duct. A small amount of airflow from the defroster duct and side window demisters is present.
• blended air temperature is available. The airflow temperature can only be cooled below the outside air temperature when A/C compressor operation has been selected by pressing the A/C request button (indicator on).
• the A/C request button is enabled. The A/C compressor operates and the indicator illuminates if the A/C request button is selected and the outside temperature is above approximately 6°C (43°F).
• the blower motor is on.

FLOOR/DEFROST

When FLOOR/DEFROST is selected:

• the RECIRC request button is enabled. If the RECIRC request button is selected (indicator on), the air inlet door closes, preventing outside air from entering the passenger compartment. If the RECIRC request button is not selected (indicator off), the air inlet door opens, allowing only outside air into the passenger compartment.
• the mode doors direct airflow to the floor duct, the defroster duct and the side window demisters.
• blended air temperature is available.
• the A/C request button is enabled. The A/C compressor operates automatically and the indicator illuminates if the A/C request button is selected and the outside temperature is above approximately 6°C (43°F).
• the blower motor is on.

DEFROST

When DEFROST is selected:

• the RECIRC request button and indicator is disabled. Regardless of button and indicator status, the air inlet door opens, allowing only outside air into the passenger compartment.
• the mode doors direct airflow to the defroster duct and side window demisters. A small amount of airflow from the floor duct is present.
• blended air temperature is available.
• the A/C request button is enabled. The A/C compressor operates automatically and the indicator illuminates if the A/C request button is selected and the outside temperature is above approximately 6°C (43°F).
• the blower motor is on.

Auxiliary Climate Control System

An auxiliary climate control system is available as optional equipment. The auxiliary climate control system operation is determined by the settings on the front or rear auxiliary climate control assembly. The auxiliary climate control assemblies include a blower motor switch and temperature control/air distribution mode knob can only be serviced as an assembly.

Auxiliary blower motor operation is enabled when the HVAC system is in any mode except OFF. The auxiliary climate control system air can only be cooled below interior air temperature when A/C compressor operation has been requested by the settings of the climate control assembly of the base (front) system. The auxiliary climate control system air can be heated at any time.

Front auxiliary climate controls

The blower motor speed can be set to OFF, LO, MED-LO, MED-HI or HI by pressing the auxiliary blower FAN "+" or "-" button. The temperature/airflow mode can be adjusted by pressing the rear TEMPERATURE "+" or "-" button. If the front (main) driver side temperature is set to full COOL or full HEAT, the auxiliary temperature is set to the same as the driver and cannot be changed. When the front auxiliary REAR button is pressed, all control of the auxiliary climate control system functions are transferred to the rear auxiliary climate control assembly and the auxiliary temperature can be independently controlled.

Rear auxiliary climate controls

The blower motor switch controls the auxiliary blower motor speed only when the front auxiliary climate control assembly blower motor switch is set to REAR. The blower motor speed can be set to OFF, LO, MED-LO, MED-HI or HI.

The temperature control is a potentiometer that tells the HVAC module the desired temperature setting. The HVAC module then moves the mode door actuator to the appropriate position. When A/C compressor operation has not been initiated (A/C compressor commanded on) by the HVAC module (as equipped), the auxiliary climate control system cannot cool the air below that of the interior air temperature.

The airflow mode control switches tell the HVAC module the desired airflow mode setting. The HVAC module then moves the mode door actuator to the appropriate position.