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 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, the following precautions must be observed.
- The A/C refrigerant of all vehicles must be identified and analyzed 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 the engine 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, 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 Automotive Service Excellence (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.
- Refrigerant R-134a 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 using approved equipment.
- 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 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 refrigerant 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 specification. 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 manual climate control system heats or cools the vehicle depending on the function selector switch position and the temperature selected.
- The function selector switch position determines heating or cooling and air distribution.
- The temperature control setting determines the air temperature.
- The heater blower motor switch varies the blower motor speed.
The Electronic Automatic Temperature Control (EATC) system maintains the selected vehicle interior temperature by heating or cooling the air.
- During A/C operation, the system also reduces the relative humidity of the air.
- The driver may override the automatic mode of operation.
The system components are the following:
- A/C compressor
- A/C compressor clutch assembly
- A/C condenser core
- A/C evaporator core
- Suction accumulator
- Connecting refrigerant lines
- A/C evaporator core orifice
- A/C cycling switch
- A/C pressure cutoff switch
- Heater core and evaporator core housing
- HVAC module
- Manual climate control assembly
- Blower switch (manual system)
- Temperature blend door actuator
- Blower motor resistor or speed control module
- Blower motor
- Ambient temperature sensor
- In-vehicle temperature sensor
- Solar radiation sensor
External Temperature Display
When the ignition is first turned ON, the external temperature displayed will be the last temperature read before the ignition was turned OFF. If the last temperature read is below 2°C (35°F), the HVAC module will prevent A/C operation.
The external temperature display will update when the vehicle has been driven above 40 km/h (25 mph) for greater than 30 seconds. Once the HVAC module updates the external temperature, the HVAC module will allow normal A/C operation.
System Air Flow Description - Manual Climate Control
MAX A/C
When MAX A/C is selected:
- The air inlet door vacuum control motor is at full vacuum, closing off outside air and admitting only recirculated air.
- The panel door and floor/defrost door vacuum control motors are at full vacuum, directing airflow to the instrument panel A/C registers.
- Blended air temperature is available.
- The A/C compressor will operate if the outside temperature is above approximately 4°C (39°F).
- The blower motor is ON.
NORM A/C
When NORM A/C is selected:
- The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- The panel door and floor/defrost door vacuum control motors are at full vacuum, directing airflow to the instrument panel A/C registers.
- Blended air temperature is available.
- The A/C compressor will operate if the outside air temperature is above approximately 4°C (39°F).
- The blower motor is ON.
VENT
When VENT is selected:
- The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- The panel door and floor/defrost door vacuum control motors are at full vacuum, directing airflow to the instrument panel A/C registers.
- The temperature can be adjusted to heat the air, but air cannot be cooled below outside temperature.
- The A/C compressor will not operate.
- The blower motor is ON.
OFF
When OFF is selected:
- The air inlet door vacuum control motor is at full vacuum, closing off outside air from entering the passenger compartment.
- The floor/defrost door vacuum control motor is at full vacuum and the panel door vacuum control motor is at no vacuum, closing off airflow to the defrost duct, side window demisters and instrument panel A/C registers.
- The A/C compressor will not operate.
- The blower motor is OFF.
FLOOR
When FLOOR is selected:
- The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- The floor/defrost door vacuum control motor is at full vacuum and the panel door vacuum control motor is at no vacuum, directing airflow to the floor duct.
- The temperature can be adjusted to heat the air, but air cannot be cooled below the outside temperature.
- The A/C compressor will not operate.
- The blower motor is ON.
MIX
When MIX is selected:
- The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- The floor/defrost door vacuum control motor is at partial vacuum and the panel door vacuum control motor is at no vacuum, directing airflow to the floor duct, the defroster duct and the side window demisters.
- Blended air temperature is available.
- The A/C compressor will operate if the outside air temperature is above approximately 4°C (39°F).
- The blower motor is ON.
DEFROST
When DEFROST is selected:
- The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- The floor/defrost door vacuum control motor and the panel door vacuum control motors are at no vacuum, directing airflow to the defroster duct and the side window demisters.
- Blended air temperature is available.
- The A/C compressor will operate if the outside air temperature is above approximately 4°C (39°F).
- The blower motor is ON.
System Airflow Description - Electronic Automatic Temperature Control (EATC)
AUTOMATIC
When AUTOMATIC is selected:
NOTE: If conditions require heat, until the engine is at operating temperature, the blower motor will operate in low and airflow will be directed to the defroster ducts.
- The air inlet door vacuum control motor is automatically controlled depending on airflow location and desired temperature.
- The panel door and floor/defrost door vacuum control motors are automatically controlled depending on desired temperature.
- Blended air temperature is available.
- The A/C compressor will operate if the outside air temperature is above approximately 4°C (39°F).
- Blower motor speed is automatically controlled. If the fan speed override button is pressed in AUTOMATIC mode, the fan speed will no longer be automatically controlled.
MAX A/C
When MAX A/C is selected:
- The air inlet door vacuum control motor is at full vacuum, closing off outside air and admitting only recirculated air.
- The panel door and floor/defrost door vacuum control motors are at full vacuum, directing airflow to the instrument panel A/C registers.
- Blended air temperature is available.
- The A/C compressor will operate if the outside temperature is above approximately 4°C (39°F).
- The blower motor is ON.
NORM A/C
When NORM A/C is selected:
- The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- The panel door and floor/defrost door vacuum control motors are at full vacuum, directing airflow to the instrument panel A/C registers.
- Blended air temperature is available.
- The A/C compressor will operate if the outside air temperature is above approximately 4°C (39°F).
- The blower motor is ON.
VENT
When VENT is selected:
- The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- The panel door and floor/defrost door vacuum control motors are at full vacuum, directing airflow to the instrument panel A/C registers.
- The temperature can be adjusted to heat the air, but air cannot be cooled below outside temperature.
- The A/C compressor will not operate.
- The blower motor is ON.
OFF
When OFF is selected:
- The air inlet door vacuum control motor is at full vacuum, closing off outside air from entering the passenger compartment.
- The floor/defrost door vacuum control motor is at full vacuum and the panel door vacuum control motor is at no vacuum, closing off airflow to the defrost duct, side window demisters and instrument panel A/C registers.
- The A/C compressor will not operate.
- The blower motor is OFF.
FLOOR
When FLOOR is selected:
- The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- The floor/defrost door vacuum control motor is at full vacuum and the panel door vacuum control motor is at no vacuum, directing airflow to the floor duct.
- The temperature can be adjusted to heat the air, but air cannot be cooled below the outside temperature.
- The A/C compressor will not operate.
- The blower motor is ON.
FLOOR/DEFROST
When FLOOR/DEFROST is selected:
- The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- The floor/defrost door vacuum control motor is at partial vacuum and the panel door vacuum control motor is at no vacuum, directing airflow to the floor duct, the defroster duct and the side window demisters.
- Blended air temperature is available.
- The A/C compressor will operate if the outside air temperature is above approximately 4°C (39°F).
- The blower motor is ON.
DEFROST
When DEFROST is selected:
- The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- The floor/defrost door and panel door vacuum control motors are at no vacuum, directing airflow to the defroster duct and the side window demisters.
- Blended air temperature is available.
- The A/C compressor will operate if the outside air temperature is above approximately 4°C (39°F).
- The blower motor is ON.