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 the 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:
- Never open or loosen a connection before recovering 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 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 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 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 switch setting determines the air temperature.
- The blower motor switch varies the blower motor speed.

The A/C system consists of the following components:

- 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 actuator
- Blower motor resistor
- Blower motor
- Auxiliary connecting refrigerant lines
- Auxiliary heater core and evaporator core housing
- Auxiliary A/C evaporator core
- Auxiliary climate control assembly
- Auxiliary blower motor
- Auxiliary blower motor resistor


System Airflow Description

MAX A/C

When MAX A/C is selected:

- the recirculation air duct door is at full vacuum, closing off outside air and admitting only recirculated air.
- the floor/panel door and the floor/defrost door are at the full vacuum position, directing airflow to the A/C register.
- the temperature is usually set for maximum cold but may be heated if desired.
- air will be picked up at the recirculation opening by the blower motor. With the A/C control set for maximum cold, airflow across the evaporator core will be diverted past the heater core and then directed into the passenger compartment through the instrument panel A/C register. There is also some airflow to the side window demisters.
- the A/C compressor will be enabled when MAX A/C is selected.
- the blower motor is ON.

NORM A/C

When NORM A/C is selected:

- the recirculation air duct door is in the no vacuum position, blocking recirculated air and admitting outside air.
- the floor/panel door and the floor/defrost door are at the full vacuum position, directing airflow to the instrument panel A/C registers.
- the temperature may be raised if desired.
- the A/C compressor will be enabled when NORM A/C is selected.
- the blower motor is ON.

VENT

When VENT is selected:

- the recirculation air duct door is in the no vacuum position, blocking recirculated air and admitting outside air.
- the floor/panel door and the floor/defrost door are at the full vacuum position, 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 be disabled when VENT is selected.
- the blower motor is ON.

OFF

When OFF is selected:

- the recirculation air duct door is at full vacuum, closing off outside air and admitting only recirculated air.
- the floor/panel door is in the no vacuum position, closing the passage to the instrument panel A/C registers.
- the floor/defrost door is at full vacuum, closing the passages to the windshield defroster hose nozzle.
- the blower motor and the A/C compressor are OFF.

FLOOR

When FLOOR is selected:

- the recirculation air duct door is in the no vacuum position, blocking recirculated air and admitting outside air.
- the floor/panel door is in the no vacuum position, blocking air circulation to the instrument panel A/C registers.
- the floor/defrost door is in the full vacuum position, directing all airflow to the heater outlet floor duct.
- the temperature can be adjusted to mix air flowing through and around the heater core to achieve the desired temperature level.
- the A/C compressor will be disabled when FLOOR is selected.
- the blower motor is ON.

MIX

When MIX is selected:

- the recirculation air duct door is in the no vacuum position blocking recirculated air and admitting outside air.
- the floor/panel door is in the no vacuum position, blocking air circulation to the instrument panel A/C registers.
- the floor/defrost door is in the partial vacuum position, allowing airflow to both the windshield defroster hose nozzle and the heater outlet floor duct. There is also some airflow to the side window demisters.
- the A/C compressor will be enabled when MIX is selected to dehumidify the air and reduce windshield fogging.
- the blower motor is ON.

DEFROST

When DEFROST is selected:

- the recirculation air duct door is in the no vacuum position, admitting outside air.
- both the floor/defrost door and the floor/panel door are in the no vacuum position so that most of the incoming air is directed to the windshield defroster hose nozzle. There is also airflow to the side window demisters.
- the temperature setting will determine the amount of air that is directed through the heater core and the amount that bypasses the heater core.
- the A/C compressor will be enabled when DEFROST is selected to dehumidify the air and reduce windshield fogging.
- the blower motor is ON.