Part 2

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 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:
- 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 or cools the vehicle depending on the function selector switch position and the temperature selected.

- The function selector switch position determines heating or cooling, air distribution and enables blower motor operation.
- The temperature control setting determines the air temperature.
- The blower motor switch varies the blower motor speed.

The Dual Automatic Temperature Control (DATC) system maintains the selected vehicle interior temperature by heating and/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 driver side and passenger side temperature settings can be individually controlled.

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 transducer
- Heater core and evaporator core housing
- HVAC module - DATC
- Manual climate control assembly
- Blower switch (manual system)
- Temperature blend door actuator(s)
- Blower motor resistor or speed control module
- Blower motor
- Ambient temperature sensor
- In-vehicle temperature sensor
- Solar radiation sensor
- 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


Auxiliary Climate Control System

NOTE: Auxiliary climate control system not available on Sport Trac model.

An auxiliary climate control system is available as optional equipment. The auxiliary climate control system operation is determined by the settings on the front auxiliary climate control assembly. The auxiliary climate control assemblies include a blower motor switch, temperature control switch and air distribution mode switch, none of which can be individually serviced.

On vehicles with manual climate control the auxiliary blower motor operation is enabled when the function selector switch is in any position except OFF. The auxiliary system air can be cooled below ambient temperature only when A/C compressor operation has been requested by the settings of the climate control assembly of the base (front) system. The auxiliary system air can be heated at any time, the heater control valve does not affect the auxiliary climate control system operation.

On vehicles with DATC the auxiliary blower motor is operational regardless of the DATC system setting. The auxiliary system air can be cooled below ambient temperature only when A/C compressor operation has been requested by the settings of the HVAC module - DATC. The auxiliary system air can be heated at any time, the heater control valve operation does not affect the auxiliary climate control system.

The front auxiliary climate control assembly:

- blower motor switch controls the auxiliary blower motor speed. The blower motor speed can be set to OFF, MED-LO, MED-HI or HI.
- air distribution mode switch toggles airflow between the overhead vents and the floor vent by outputting signals to the auxiliary airflow mode door actuator which positions the auxiliary airflow mode door in all blower motor switch positions. Back-lit icons on the front climate control display indicate the source of the auxiliary system airflow.
- temperature control switch is a potentiometer that outputs a variable voltage to the auxiliary temperature blend door actuator to set the position of the auxiliary temperature blend door in all blower motor switch positions. The temperature of the auxiliary system air may be affected by the manual climate control assembly or HVAC module - DATC settings (as equipped). When A/C compressor operation has not been initiated (A/C compressor commanded on) by the manual climate control assembly or the HVAC module - DATC (as equipped), the auxiliary climate control system cannot cool the air below that of the ambient temperature.


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 door vacuum control motor is at full vacuum and the defrost door and floor door vacuum control motors are at no vacuum, directing airflow to the instrument panel A/C registers. A small amount of airflow from the floor duct, defroster duct and side window demisters will be present.
- the heater control valve is at full vacuum when the temperature selection is in the full COOL position, preventing the flow of hot coolant to the heater core. Otherwise, blended air temperature is available.
- air will be drawn from the recirculated air inlet by the blower motor. When the temperature selection is in the full COOL position, the airflow will be diverted past the heater core and then into the passenger compartment through the instrument panel A/C registers.
- the A/C request switch will be illuminated and will be disabled.
- The A/C compressor will not operate if the outside air temperature is below -1°C (30°F). The A/C compressor will resume operation when the outside air temperature rises above 2°C (35°F).
- the blower motor is ON.
- the auxiliary blower motor is enabled, if equipped.

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 door vacuum control motor is at full vacuum and the defrost door and floor door vacuum control motors are at no vacuum, directing airflow to the instrument panel A/C registers. A small amount of airflow from the floor duct, defroster duct and side window demisters will be present.
- the heater control valve is at full vacuum when the temperature selection is in the full COOL position, preventing the flow of hot coolant to the heater core. Otherwise, blended air temperature is available.
- the A/C request switch will be enabled. The A/C compressor can operate and the indicator will be illuminated if the A/C request switch is selected and if the outside air temperature is not below -1°C (30°F). If the outside air temperature has gone below -1°C (30°F), A/C compressor operation will resume when the outside air temperature rises above 2°C (35°F).
- the blower motor is ON.
- the auxiliary blower motor is enabled, if equipped.

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 door and floor door vacuum control motors are at full vacuum and the defrost door vacuum control motor is at no vacuum, directing airflow to the floor duct and the instrument panel A/C registers. A small amount of airflow from the defroster duct and side window demisters will be present.
- the heater control valve is at full vacuum when the temperature selection is in the full COOL position, preventing the flow of hot coolant to the heater core. Otherwise, blended air temperature is available.
- the A/C request switch will be enabled. The A/C compressor can operate and the indicator will be illuminated if the A/C request switch is selected and if the outside air temperature is not below -1°C (30°F). If the outside air temperature has gone below -1°C (30°F), A/C compressor operation will resume when the outside air temperature rises above 2°C (35°F).
- the blower motor is ON.
- the auxiliary blower motor is enabled, if equipped.

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 defrost door vacuum control motor is at full vacuum and the panel door and floor door vacuum control motors are at no vacuum, closing off airflow to the passenger compartment outlets.
- the heater control valve is at full vacuum when the temperature selection is in the full COOL position, preventing the flow of hot coolant to the heater core.
- the A/C request switch is disabled.
- the blower motor is OFF.
- the auxiliary blower motor is disabled, if equipped.

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 door and defrost door vacuum control motors are at full vacuum and the panel door vacuum control motors are at no vacuum, directing airflow to the floor duct and the defroster duct. A small amount of airflow from the instrument panel A/C registers, defroster duct and side window demisters will be present.
- the heater control valve is at full vacuum when the temperature selection is in the full COOL position, preventing the flow of hot coolant to the heater core. Otherwise, blended air temperature is available.
- the A/C request switch will be enabled. The A/C compressor can operate and the indicator will be illuminated if the A/C request switch is selected and if the outside air temperature is not below -1°C (30°F). If the outside air temperature has gone below -1°C (30°F), A/C compressor operation will resume when the outside air temperature rises above 2°C (35°F).
- the blower motor is ON.
- the auxiliary blower motor is enabled, if equipped.

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 door vacuum control motor is at full vacuum and the defrost door and panel door vacuum control motors are at no vacuum, directing airflow to the floor duct, the defroster duct and the side window demisters. A small amount of airflow from the instrument panel A/C registers will be present.
- the heater control valve is at full vacuum when the temperature selection is in the full COOL position, preventing the flow of hot coolant to the heater core. Otherwise, blended air temperature is available.
- the A/C request switch will not illuminate and will be disabled. To reduce fogging, the A/C compressor will operate automatically if the outside air temperature is not below -1°C (30°F). If the outside air temperature has gone below -1°C (30°F), A/C compressor operation will resume when the outside air temperature rises above 2°C (35°F).
- the blower motor is ON.
- the auxiliary blower motor is enabled, if equipped.

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 door, panel door and 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 instrument panel A/C registers and floor duct will be present.
- the heater control valve is at full vacuum when the temperature selection is in the full COOL position, preventing the flow of hot coolant to the heater core. Otherwise, blended air temperature is available.
- the A/C request switch will not illuminate and will be disabled. To reduce fogging, the A/C compressor will operate automatically if the outside air temperature is not below -1°C (30°F). If the outside air temperature has gone below -1°C (30°F), A/C compressor operation will resume when the outside air temperature rises above 2°C (35°F).
- the blower motor is ON.
- the auxiliary blower motor is enabled, if equipped.


System Airflow Description - Dual Automatic Temperature Control (DATC) System

AUTO

When AUTO is selected:

- the temperature control setting(s) is/are manually set to the desired setting(s).
- the air inlet door vacuum control motor is controlled by the HVAC module - DATC, based on the temperature settings.
- the mode door vacuum control motors are controlled by the HVAC module - DATC, based on the temperature settings.
- the heater control valve is by the HVAC module - DATC based on the temperature settings.
- the A/C request is controlled by the HVAC module - DATC based on the temperature settings. The A/C compressor will not operate if the outside air temperature is below -1°C (30°F). The A/C compressor will resume operation when the outside air temperature rises above 2°C (35°F).
- the A/C request switch or the RECIRC button, if pressed, will transfer the system to manual operation.
- the blower motor is ON. The blower motor speed is automatically controlled by the HVAC module - DATC based on the temperature settings, but can be manually overridden.

OFF

When OFF is selected:

- the air inlet door vacuum control motor is at full vacuum, closing off outside air to the passenger compartment.
- the defrost door vacuum control motor is at full vacuum and the floor door and panel door vacuum control motors are at no vacuum, closing off airflow to the passenger compartment outlets.
- the heater control valve is at full vacuum, preventing the flow of hot coolant to the heater core.
- the blower motor is OFF.

PANEL

When PANEL is selected:

- the RECIRC button is enabled. If the RECIRC button is pressed (indicator ON) the air inlet door vacuum control motor is at full vacuum, closing off outside air to the passenger compartment. If the RECIRC button is not selected (indicator OFF), the air inlet door vacuum control motor will be at no vacuum, admitting only outside air into the passenger compartment.
- the defrost door and panel door vacuum control motors are at full vacuum and the 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 floor duct, defroster duct and side window demisters will be present.
- the heater control valve is controlled by the HVAC module - DATC based on the temperature settings.
- temperature control can be adjusted by directing the airflow through and around the heater core. Only when A/C compressor operation has been selected by pressing the A/C request switch (indicator ON) can the airflow temperature be cooled below that of the ambient (outside) air temperature.
- the A/C request switch is enabled. When the A/C request switch is pressed (indicator ON), the A/C compressor can operate if the outside air temperature is not below -1°C (30°F). If the outside air temperature has gone below -1°C (30°F), A/C compressor operation will resume when the outside air temperature rises above 2°C (35°F).
- the blower motor is ON.

PANEL/FLOOR

When PANEL/FLOOR is selected:

- the RECIRC button is enabled. If the RECIRC button is pressed (indicator ON), the air inlet door vacuum control motor is at full vacuum, closing off outside air to the passenger compartment. If the RECIRC button is not selected (indicator OFF) the air inlet door vacuum control motor will be at no vacuum, admitting only outside air into the passenger compartment.
- the defrost door, panel door and floor door vacuum control motors are at full vacuum, directing airflow to the instrument panel A/C registers and to the floor duct. A small amount of airflow from the defroster duct and side window demisters will be present.
- the heater control valve is controlled by the HVAC module - DATC based on the temperature settings.
- temperature control can be adjusted by directing the airflow through and around the heater core. Only when A/C compressor operation has been selected by pressing the A/C request switch (indicator ON) can the airflow temperature be cooled below that of the ambient (outside) air temperature.
- the A/C request switch is enabled. When the A/C request switch is pressed (indicator ON), the A/C compressor can operate if the outside air temperature is not below -1°C (30°F). If the outside air temperature has gone below -1°C (30°F), A/C compressor operation will resume when the outside air temperature rises above 2°C (35°F).
- the blower motor is ON.

FLOOR

When FLOOR is selected:

- the RECIRC button is enabled. If the RECIRC button is pressed (indicator ON), the air inlet door vacuum control motor is at full vacuum, closing off outside air to the passenger compartment. A RECIRC door time-out strategy will be used to prevent fogging and the RECIRC function will automatically be turned off after approximately 4 minutes. If the RECIRC button is not selected (indicator OFF), the air inlet door vacuum control motor will be at no vacuum, admitting only outside air into the passenger compartment.
- the defrost door and floor door vacuum control motors are at full vacuum and the panel door vacuum control motor is at no vacuum, directing airflow to the floor duct. A small amount of airflow from the instrument panel A/C registers, defroster duct and side window demisters will be present.
- the heater control valve is controlled by the HVAC module - DATC based on the temperature settings.
- temperature control can be adjusted by directing the airflow through and around the heater core. Only when A/C compressor operation has been selected by pressing the A/C request switch (indicator ON) can the airflow temperature be cooled below that of the ambient (outside) air temperature.
- the A/C request switch is enabled. When the A/C request switch is pressed (indicator ON), the A/C compressor can operate if the outside air temperature is not below -1°C (30°F). If the outside air temperature has gone below -1°C (30°F), A/C compressor operation will resume when the outside air temperature rises above 2°C (35°F).
- the blower motor is ON.

FLOOR/DEFROST

When FLOOR/DEFROST is selected:

- the RECIRC button is disabled. The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- the floor door vacuum control motor is at full vacuum and the defrost door and panel door vacuum control motors are at no vacuum, directing airflow to the floor duct, defroster duct and side window demisters. A small amount of airflow from the instrument panel A/C registers will be present.
- the heater control valve is controlled by the HVAC module - DATC based on the temperature settings.
- temperature control can be adjusted by directing the airflow through and around the heater core.
- the A/C request switch will be disabled and will not illuminate. The A/C compressor will operate automatically if the outside air temperature is not below -1°C (30°F). If the outside air temperature has gone below -1°C (30°F), A/C compressor operation will resume when the outside air temperature rises above 2°C (35°F).
- the blower motor is ON.

DEFROST

When DEFROST is selected:

- the RECIRC button is disabled. The air inlet door vacuum control motor is at no vacuum, admitting only outside air into the passenger compartment.
- the floor door, defrost door and panel door vacuum control motors are at no vacuum, directing airflow to the defroster duct and side window demisters. A small amount of airflow from the instrument panel A/C registers and the floor duct will be present.
- the heater control valve is controlled by the HVAC module - DATC based on the temperature settings.
- temperature control can be adjusted by directing the airflow through and around the heater core.
- the A/C request switch will be disabled and will not illuminate. The A/C compressor will operate automatically if the outside air temperature is not below -1°C (30°F). If the outside air temperature has gone below -1°C (30°F), A/C compressor operation will resume when the outside air temperature rises above 2°C (35°F).
- the blower motor is ON.