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 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, 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 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, the following precautions must be observed.

- 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 mineral 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 manual climate control system heats and/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 blower motor switch varies the blower motor speed.
- During A/C operation the system also reduces the relative humidity of the air.

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
- Manual climate control assembly
- Blower switch
- Temperature blend door actuators
- Blower motor resistor
- Blower motor


System Airflow 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/defrost door vacuum control motor is at full vacuum and the panel/floor door vacuum control motor is at no vacuum, directing airflow to the instrument panel A/C registers. A small amount of airflow from the side window demisters will be present.
- The heater control valve is at full vacuum, preventing the flow of hot coolant to the heater core. Blended air temperature is not available.
- The A/C compressor will operate if the outside temperature is above approximately 6°C (43°F).
- The blower motor is ON.

A/C

When 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/defrost door vacuum control motor is at full vacuum and the panel/floor door vacuum control motor is at no vacuum, directing airflow to the instrument panel A/C registers. A small amount of airflow from the side window demisters will be present.
- The heater control valve is at no vacuum, allowing the flow of hot coolant to the heater core. Blended air temperature is available.
- The A/C compressor will operate if the outside temperature is above approximately 6°C (43°F).
- The blower motor is ON.

PANEL

When PANEL is selected:

- The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- The panel/defrost door vacuum control motor is at full vacuum and the panel/floor door vacuum control motor is at no vacuum, directing airflow to the instrument panel A/C registers. A small amount of airflow from the side window demisters will be present.
- The heater control valve is at no vacuum, allowing the flow of hot coolant to the heater core. Blended air temperature is available.
- The temperature can be adjusted to heat the air, but the air cannot be cooled below the outside temperature.
- The blower motor is ON.
- The A/C compressor will not operate.

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 panel/floor door vacuum control motor is at full vacuum and the panel/defrost door vacuum control motor is at no vacuum, closing off airflow to the defrost duct, side window demisters, the floor duct and the instrument panel A/C registers. A small amount of airflow from the side window demisters will be present.
- The heater control valve is at full vacuum, preventing the flow of hot coolant to the heater core.
- The A/C compressor will not operate.
- The blower motor is OFF.

PANEL/FLOOR

When PANEL/FLOOR is selected:

- The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- The panel/defrost door vacuum control motor is at full vacuum and the panel/floor door vacuum control motor is at partial vacuum, directing airflow to the floor duct and the instrument panel A/C registers. A small amount of airflow from the side window demisters will be present.
- The heater control valve is at no vacuum, allowing the flow of hot coolant to the heater core. Blended air temperature is available.
- The A/C compressor will operate if the outside temperature is above approximately 6°C (43°F).
- The blower motor is ON.

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 panel/floor door vacuum control motor is at full vacuum and the panel/defrost door vacuum control motor is at no vacuum, directing airflow to the floor duct. A small amount of airflow from the side window demisters will be present.
- The heater control valve is at no vacuum, allowing the flow of hot coolant to the heater core. Blended air temperature is available.
- The temperature can be adjusted to heat the air, but the 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 panel/floor door vacuum control motor is at partial vacuum and the panel/defrost door vacuum control motor is at no vacuum, directing airflow to the floor duct, the defroster duct and the side window demisters. A small amount of airflow from the side window demisters will be present.
- The heater control valve is at no vacuum allowing the flow of hot coolant to the heater core. Blended air temperature is available.
- The temperature can be adjusted to heat or cool the air below the outside temperature.
- The A/C compressor will operate if the outside temperature is above approximately 6°C (43°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 panel/floor door and panel/defrost door vacuum control motors are at no vacuum, directing airflow to the defroster duct and the side window demisters. A small amount of airflow from the side window demisters will be present.
- The heater control valve is at no vacuum allowing the flow of hot coolant to the heater core. Blended air temperature is available.
- The temperature can be adjusted to heat or cool the air below the outside temperature.
- The A/C compressor will operate if the outside temperature is above approximately 6°C (43°F).
- The blower motor is ON.