Climate Control System
Climate Control System
Climate Control System Operation
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 MSDS sheet from the manufacturer). Decomposition products are hydrofluoric acid, carbon dioxide and water.
Failure to follow these instructions may result in serious personal injury.
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 requires the use of R-134a refrigerant. These 2 types of refrigerant must never be mixed. Doing so can damage the A/C system.
- Charge the A/C system with R-134a refrigerant gas while the engine is running only at the low-pressure side to prevent refrigerant slugging from damaging the A/C compressor.
- Use only R-134a refrigerant. Due to environmental concerns, when the A/C system is drained, collect the refrigerant 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 Mobile Air Conditioning Society (MACS). Use of a recovery machine dedicated to R-134a is necessary to reduce 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 described as direct substitutes for 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 R-134a refrigerant.
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 will absorb 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 will prevent condensation from forming inside a component that is cooler than the surrounding air.
The climate control system, not equipped with A/C, consists of the following components:
- Heater core and evaporator core housing
- HVAC module
- Instrument Panel Cluster (IPC)
- Temperature blend door actuator
- Floor/defrost/panel mode door actuator
- Air inlet mode door actuator
- Blower motor resistor
- Blower motor
The climate control system, equipped with A/C, consists of the following components:
- A/C compressor
- A/C compressor clutch assembly
- A/C condenser core
- A/C evaporator core
- Receiver/drier
- Connecting refrigerant lines
- Thermostatic Expansion Valve (TXV)
- Heater core and evaporator core housing
- HVAC module
- Instrument Panel Cluster (IPC)
- Temperature blend door actuator
- Floor/defrost/panel mode door actuator
- Air inlet mode door actuator
- Blower motor resistor
- Blower motor
- Evaporator discharge air temperature sensor
HVAC System Operation
The Electronic Manual Temperature Control (EMTC) system heats or cools the vehicle depending on the HVAC control panel selection.
- The control panel selection determines heating or cooling, air distribution and enables blower motor operation.
- The temperature control setting determines the air outlet temperature.
- The blower motor switch varies the blower motor speed.
- During A/C operation (if equipped), the system reduces the relative humidity of the air inside the vehicle.
HVAC System Airflow and Mode Description
Max A/C (if equipped)
When MAX A/C is selected:
- the air inlet door closes off outside air and admits only recirculated air.
- the RECIRC button is disabled and the indicator is illuminated. (RECIRC forced on)
- the defrost/panel/floor door directs airflow to the instrument panel registers.
- blended air temperature is available.
- the A/C request button disabled and the indicator is illuminated.
- the A/C compressor operates if the outside temperature is above approximately 0°C (32°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 off outside air from entering the passenger compartment. If the RECIRC request button is not selected (indicator off), the air inlet door admits only outside air into the passenger compartment.
- the defrost/panel/floor door directs airflow to the instrument panel registers.
- blended air temperature is available. Only when A/C compressor operation (if equipped) has been selected by pressing the A/C request button (indicator on), can the airflow temperature be cooled below the outside air temperature.
- the A/C request button (if equipped) 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 0°C (32°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 off outside air from entering the passenger compartment. If the RECIRC request button is not selected (indicator off), the air inlet door admits only outside air into the passenger compartment.
- the defrost/panel/floor door directs 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. Only when A/C compressor operation (if equipped) has been selected by pressing the A/C request button (indicator on), can the airflow temperature be cooled below the outside air temperature.
- the A/C request button (if equipped) 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 0°C (32°F).
- the blower motor is on.
OFF
When OFF is selected:
- the RECIRC request button is disabled.
- the air inlet door closes off outside air and admits only recirculated air.
- the A/C request button (if equipped) is disabled.
- 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 off outside air from entering the passenger compartment. If the RECIRC request button is not selected (indicator off), the air inlet door admits only outside air into the passenger compartment. When RECIRC is selected, the air inlet mode door remains in recirculated air mode for 5 minutes. After 5 minutes, the RECIRC indicator turns off and the air inlet mode door changes to fresh air mode.
- the defrost/panel/floor door directs 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. Only when A/C compressor operation (if equipped) has been selected by pressing the A/C request button (indicator on), can the airflow temperature be cooled below the outside air temperature.
- 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 0°C (32°F).
- the blower motor is on.
FLOOR/DEFROST
When the FLOOR/DEFROST is selected:
- the RECIRC request button is enabled. If the RECIRC request button is selected (indicator on), the air inlet door closes off outside air from entering the passenger compartment. If the RECIRC request button is not selected (indicator off), the air inlet door admits only outside air into the passenger compartment. When RECIRC is selected, the air inlet mode door remains in recirculated air mode for 5 minutes. After 5 minutes, the RECIRC indicator turns off and the air inlet mode door changes to fresh air mode.
- the defrost/panel/floor door actuator directs airflow to the floor duct, the defroster duct and the side window demisters.
- blended air temperature is available.
- the A/C request button (if equipped) indicates the last status and the indicator can be toggled. To reduce fogging, the A/C compressor operates automatically, regardless of indicator status, if the outside temperature is above approximately 0°C (32°F).
- the blower motor is on.
DEFROST
When DEFROST is selected:
- the RECIRC request button is disabled. The air inlet door opens, admitting only outside air into the passenger compartment.
- the defrost/panel/floor door directs 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 (if equipped) will indicate the last status and the indicator can be toggled. To reduce fogging, the A/C compressor will operate automatically, regardless of indicator status, if the outside temperature is above approximately 0°C (32°F).
- the blower motor is on.