HVAC System - Control Components: Other Ford Taurus IV facelift

Control Components - Manual Climate Control

The manual climate control system heats or cools the vehicle interior depending on the function selector switch (19B888) position and the temperature selected. The function selector switch position determines heating or cooling and air distribution. The temperature blend control setting determines air temperature.

The manual climate control system components are used to select

1. Air inlet source (outside or recirculated)
2. Blower motor speed
3. Discharge air temperature (temperature blend)
4. Discharge air location (defrost, panel, floor)
5. A/C compressor clutch (19703) operation

Control System Inputs

The climate control assembly has four system controls

Function Selector Switch

The function selector switch (19B888) is separately serviceable from the integrated control panel (ICP) (18C858), and combines a vacuum selector valve with two electrical switches to supply battery voltage (B+) to the A/C clutch circuit and the blower motor speed control circuit.

Temperature Control Switch

The temperature control switch (19C733) is separately serviceable from the integrated control panel (ICP) (18C858). Temperature selection is accomplished with a potentiometer connected to the electric blend door. Movement of the temperature control switch from COOL (blue) to WARM (Red) causes a corresponding movement of the temperature blend door.

Blower Motor Switch

The blower motor switch (19986) is separately serviceable from the integrated control panel (ICP) (18C858), and controls blower motor speed by adding or by passing resistors in the heater blower motor switch resistor (19A706).

Evaporator Discharge Air Temperature Sensor

The PCM (12A696) determines A/C compressor clutch cycling based on input from the evaporator air discharge temperature sensor (19C734). The evaporator air discharge temperature sensor

1. Maintains evaporator core temperature, and prevents icing of the evaporator core (19860) by disengaging the A/C compressor (19703) when the evaporator discharge air temperature falls below a preset level, and engaging the A/C compressor when evaporator discharge air temperature rises above a preset level. For information regarding operating temperature specifications, refer to «CLIMATE CONTROL SYSTEM-GENERAL INFORMATION»(ref-212118) .
2. Contains a thermistor which receives a reference voltage from the PCM. The thermistor then varies the resistance to the reference voltage based on the evaporator discharge air temperature, and returns the resulting voltage to the PCM. The PCM determines evaporator air discharge temperature based on the return voltage value.
3. Is located in the heater core and evaporator core housing just downstream of the evaporator airflow.

Heater Blower Motor Resistor

The heater blower motor resistor (19A706) has the following features

1. The assembly is located in the passenger compartment on the heater core and evaporator core housing (19850) next to the blower motor assembly (19805).
2. Three resistor elements are mounted on the resistor board to provide four blower motor speeds.
3. Depending on the heater blower motor switch position, series resistance is added or bypassed in the A/C blower motor circuit to decrease or increase A/C blower motor speed.
4. An overheating device (thermal limiter) will open the resistor coil when the temperature reaches 121°C (250°F) interrupting the blower motor operation in all speeds except high.
5. The thermal limiter cannot be reset and is not serviceable

Temperature Blend Door Actuator

The temperature blend door actuator (19E616) is located on the rear of the A/C evaporator housing.

1. Its function is to move the air temperature blend doors on command from the temperature control switch.

Vacuum Control Motors

The vacuum control motors (18A318)

1. Are located on the A/C evaporator housing, A/C recirculating air duct (19C590) and heater air plenum chamber (18471).
2. Direct system airflow to the vehicle interior as determined by the function selector switch.

Control Components - Electronic Automatic Temperature Control (EATC)

With the use of a microcontroller, the remote climate control module (18C612) analyzes input from the following major sources

1. Integrated control panel (temperature, air distribution and blower selection)
2. In-vehicle temperature
3. Ambient temperature
4. Sunload
5. Vehicle speed
6. Engine coolant temperature

Using these inputs, the microcontroller determines the correct conditions for the following outputs

1. A/C compressor (19703) operation
2. Blower speed
3. Air temperature blend door position
4. Airflow mode door position
5. Defroster door position
6. Air inlet door position

Integrated Control Panel

The integrated control panel (ICP) (18C858) combines the audio unit and climate controls as an assembly. The ICP has the following climate control features

1. It is used to supply the remote climate control module (18C612) with function/mode selection information.
2. It contains a blower speed override control for manual input
3. It has a vacuum fluorescent display for displaying set temperature, ambient temperature, function and diagnostic trouble codes (DTCs)

Remote Climate Control (RCC) Module

The remote climate control module is used to control the climate control system based on input from the ICP. The remote climate control module has the following features.

1. It is mounted to the heater core and evaporator core housing (19850), to the left of the blower motor.
2. It communicates with the ICP using the CAN network.
3. Uses an On-Board Diagnostic (OBD) feature to supply the technician with diagnostic trouble codes (DTCs). These DTCs direct the technician to the inoperative component.

The PCM (12A696) determines A/C compressor clutch cycling based on input from the evaporator air discharge temperature sensor (19C734). The evaporator air discharge temperature sensor

1. Maintains evaporator core temperature, and prevents icing of the evaporator core by disengaging the A/C compressor (19703) when the evaporator discharge air temperature falls below a preset level, and engaging the A/C compressor when evaporator discharge air temperature rises above a preset level. For information regarding operating temperature specifications, refer to «CLIMATE CONTROL SYSTEM-GENERAL INFORMATION»(ref-212118) .
2. Contains a thermistor which receives a reference voltage from the PCM. The thermistor then varies the resistance to the reference voltage based on the evaporator discharge air temperature, and returns the resulting voltage to the PCM. The PCM determines evaporator air discharge temperature based on the return voltage value.
3. Is located in the heater core and evaporator core housing just downstream of the evaporator airflow.

A/C Ambient Air Temperature Sensor

The A/C ambient air temperature sensor (19E702)

1. Is located in front of the A/C condenser core (19712) near the center of the vehicle.
2. Contains a thermistor which measures the temperature of outside air as a resistance and sends that reading to the RCC module.

In-Vehicle Temperature Sensor

The in-vehicle temperature sensor (19C734) operates in the following manner

1. A thermistor in the in-vehicle temperature sensor measures air temperature inside the passenger compartment.
2. An automatic temperature control sensor hose and elbow (19D888) is connected between the A/C evaporator housing (19850) and the in-vehicle temperature sensor.
3. The automatic temperature control sensor hose and elbow takes air from the A/C evaporator housing air stream to create a suction in the in-car temperature sensor.
4. The suction draws in-vehicle air into the in-vehicle temperature sensor and across the thermistor.

Solar Amplifier (Sunload Sensor)

For additional information on the location and service of the solar amplifier (13A018), refer to EXTERIOR LIGHTING .

A/C Blower Motor Speed Control

The A/C blower motor speed control (19E624) is located under the A/C evaporator housing, near the blower motor (19805).

1. The function of the A/C blower motor speed control is to convert low power signals from the RCC module to a high current, variable ground feed for the blower motor.
2. A/C blower motor speed is infinitely variable and is controlled by the RCC module software.
3. A delay function provides a gradual increase or decrease in blower motor speed under all conditions.

A/C Electronic Blend Door Actuator

The A/C electronic blend door actuator (19E616) is located on the rear of the A/C evaporator housing.

1. Its function is to move the air temperature blend doors on command from the control assembly.
2. The A/C electronic blend door actuator contains a reversible electric motor and a potentiometer. The potentiometer wiper is connected to the actuator output shaft and moves with the output shaft to indicate the position of the air temperature blend door.
3. A 5 volt signal is applied to the ends of the potentiometer. The voltage available at the wiper indicates the position of the potentiometer. The expressed value of the actuator wiper voltage is sent to the electronic automatic temperature control module and is matched with the wiper voltage of the module potentiometer. The control module then drives the actuator motor in whichever direction is necessary to make the actuator wiper voltage agree with the control module wiper voltage.

The vacuum control motors (18A318)

1. Are located on the A/C evaporator housing, air inlet duct (19C590) and plenum chamber (18471).
2. Direct system airflow to the vehicle interior as determined by the RCC module or manual override.

Refer to CLIMATE CONTROL SYSTEM-GENERAL INFORMATION .

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Scheme 35

1. Using the special tool, pull out the integrated control panel (18C858).
2. Label and disconnect the electrical connectors. Remove the integrated control panel.
3. Label and disconnect the electrical connectors and the in-car temperature sensor hose (19D888). Remove the integrated control panel.
4. To install, reverse the removal procedure.

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Scheme 41

1. Remove the integrated control panel. For additional information, refer to «CLIMATE CONTROL ASSEMBLY»(ref-212123-S13482399942005122300000) .
2. Remove the right-side lower instrument panel insulator.
3. Open the glove compartment. Pressing the tabs inward, lower the glove compartment towards the floor.
4. Remove the screw.
5. Remove the screw.
6. Disconnect the remote climate control (RCC) module electrical connector.
7. Remove the two nuts. Disconnect the plenum vacuum harness. Remove the RCC module (18C612).
8. To install, reverse the removal procedure.

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Scheme 43

1. Remove the integrated control panel (18C858). For additional information, refer to «CLIMATE CONTROL ASSEMBLY»(ref-212123-S13482399942005122300000) .
2. Remove the knob (18519).
3. Remove the screw. Rotating the blower motor switch counterclockwise, remove the blower motor switch (19986).
4. To install, reverse the removal procedure.

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1. Remove the integrated control panel (18C858). For additional information, refer to «CLIMATE CONTROL ASSEMBLY»(ref-212123-S13482399942005122300000) .
2. Remove the knob (18519).
3. Remove the screw. Rotating the temperature control switch clockwise, remove the temperature control switch (19C733).
4. To install, reverse the removal procedure.

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Scheme 47

1. Remove the integrated control panel (18C858). For additional information, refer to «CLIMATE CONTROL ASSEMBLY»(ref-212123-S13482399942005122300000) .
2. Remove the knob (18519).
3. Disengage the retaining tabs. Remove the function selector switch (19B888).
4. To install, reverse the removal procedure.

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1. Remove the four scrivets and the grille.
2. Detach the ambient air temperature sensor (12A647).
3. Disconnect the ambient air temperature sensor.
4. To install, reverse the removal procedure.

Scheme 51

1. Remove the integrated control panel (18C858). For additional information, refer to «CLIMATE CONTROL ASSEMBLY»(ref-212123-S13482399942005122300000) .
2. While pressing the retaining tabs inward, remove the in-car temperature sensor (19C734).
3. To install, reverse the removal procedure.

Sunload Sensor

For additional information, refer to EXTERIOR LIGHTING .

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1. Lower the glove compartment door.
2. Disconnect the evaporator air discharge temperature sensor electrical connector.
3. Carefully pry the evaporator air discharge temperature sensor (19C734) to disengage the clips and remove the evaporator air discharge temperature sensor.
4. To install, reverse the removal procedure.

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Scheme 56

1. Remove the right-side lower instrument panel insulator.
2. Remove the temperature blend door linkage shield.
3. Remove the temperature blend door actuator (19E660). Disconnect the electrical connector. Remove the screws. Remove the temperature blend door actuator.
4. To install, reverse the removal procedure.

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1. Remove the right-side instrument panel insulator (046A42).
2. Remove the blower motor resistor (18591). Disconnect the electrical connector. Remove the screws. Remove the blower motor resistor.
3. To install, reverse the removal procedure.

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Scheme 60

1. Remove the right-side instrument panel insulator.
2. Remove the blower motor speed control (19E624). Disconnect the vacuum line. Disconnect the electrical connectors. Remove the screws and the blower motor speed control.
3. To install, reverse the removal procedure.

Scheme 61

1. Remove the evaporator and heater core housing (19850). For additional information, refer to «HEATING & VENTILATION»(ref-212120) .
2. Remove the screws.
3. Rotate and remove the air inlet door vacuum control motor (18A318).
4. To install, reverse the removal procedure.