HVAC System - Control Components: Other Ford Thunderbird XI

Dual Electronic Automatic Temperature Control

With the use of a microcontroller, the dual automatic temperature control (DATC) module analyzes input from the following major sources

1. temperature, function and blower selection (made by the vehicle occupants)
2. in-vehicle temperature sensor
3. ambient temperature sensor
4. dual sunload sensor
5. vehicle speed
6. engine rpm
7. engine coolant temperature
8. actuator door position controls
9. driver and passenger heater core air discharge temperature sensors
10. evaporator discharge temperature

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

1. A/C clutch engagement
2. blower speed
3. cold air bypass door position
4. panel door position
5. defrost door position
6. floor door position
7. air inlet duct door position
8. driver coolant control valve
9. passenger driver coolant control valve
10. electric water pump (3.9L engine)
11. heater wiper rest or heated windshield
12. heated rear window rear defog
13. external temperature (outside temperature display)

Scheme 257

A/C Ambient Air Temperature Sensor

The A/C ambient air temperature sensor

1. is located on the grille opening reinforcement behind the grille 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 dual automatic temperature control assembly.

In-Vehicle Temperature Sensor

The in-vehicle temperature sensor is located in the instrument cluster finish panel. The sensor 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 is connected between the A/C plenum housing and the in-vehicle temperature sensor.
3. The automatic temperature control sensor hose and venturi takes air from the A/C plenum housing to create a suction across the in-vehicle temperature sensor.
4. The suction draws in-vehicle air into the in-vehicle temperature sensor and across the thermistor.

Dual A/C Sunload Sensor

The dual A/C sunload sensor

1. is located on the top center of the instrument panel in the defroster grille.
2. contains photovoltaic diodes that are sensitive to sunlight.
3. generates small amounts of current across the terminals depending upon the amount of light reaching the photovoltaic diode; therefore the only test that can be carried out is for an internal short circuit, an open circuit or sensor value out-of-range.
4. contains an internal diagnostic resistor to allow the DATC module to detect a difference between an open circuit and no sunlight.

A/C Blower Motor Speed Control

The A/C blower motor speed control is located on the A/C evaporator housing.

1. The function of the A/C blower motor speed control is to convert low power signals from the dual electronic automatic temperature control module to a high current, variable ground feed for the blower motor.
2. Blower motor speed is infinitely variable and is controlled by the dual electronic automatic temperature control module software.
3. A delay function provides a gradual increase or decrease in blower motor speed under all conditions.
4. Controls the integral high blower relay which is engaged when maximum fan speed is selected.

A/C Electronic Air Inlet Door Actuator

The A/C electronic air inlet door actuator is located on the evaporator housing. The air inlet door position determines whether outside or recirculated air is being used.

1. The actuator positions the air inlet door on command from the control assembly.
2. The air inlet door actuator contains a reversible electric motor and a potentiometer.
3. A 5 volt signal and ground reference is applied to the ends of the potentiometer. The voltage available at the wiper indicates the position of the potentiometer. The target position of the actuator is calculated by the DATC module and is matched with the wiper voltage of the actuator. The control module will drive the actuator motor in the direction necessary to make the actuator wiper voltage agree with the control module target position.

Cold Air Bypass Door Actuator

The cold air bypass door actuator is located on the evaporator core housing. During automatic operation the control module can position the door fully open so that some of the airflow will not pass through the heater core. This will provide for maximum cooling. The door is closed or partially closed during modes other than maximum cooling.

1. The cold air bypass door actuator positions the cold air bypass door on command from the DATC module.
2. Operation of the cold air bypass door actuator is the same as the air inlet door.

Defrost Door Actuator

The defrost door actuator is located on the plenum chamber. The actuator will position the defrost door fully open during defrost operation, partially open during floor/defrost and floor mode operation and fully closed during all other operations.

1. The defrost door actuator positions the defrost door on command from the DATC module.
2. Operation of the defrost door actuator is the same as the air inlet door.

Panel Door Actuator

The panel door actuator is located on the plenum chamber. The actuator operates the panel door. The actuator positions the panel door fully open during panel mode and partially open during floor/panel operation. The door is closed during other operations.

1. The panel door actuator positions the panel door on command from the DATC module.
2. Operation of the panel door actuator is the same as the air inlet door.

Floor Outlet Door Actuator

The floor outlet door actuator positions the floor outlet door fully open during floor and floor/panel and floor/defrost operations. The door is closed during other operations.

1. The floor outlet door actuator positions the floor outlet door on command from the DATC module.
2. Operation of the floor door actuator is the same as the air inlet door.
3. The floor outlet door actuator is in the full open position in OFF mode.

Scheme 258

Scheme 259

Scheme 260

Scheme 261

Scheme 262

1. Disconnect the battery. For additional information, refer to «BATTERY, MOUNTING & CABLES»(ref-204581) .
2. Remove the lower instrument panel trim piece.
3. Remove the screws and position aside the switch panel.
4. Insert a mini-pick in the center register and pull the center register from the instrument panel. If equipped, disconnect the connector.
5. Remove the screws and pull the DATC and radio assembly away from the instrument panel.
6. Disconnect the two connectors.
7. Remove the four screws (two on each side of the control assembly) and remove the dual automatic temperature control assembly.
8. To install, reverse the removal procedure.

Scheme 263

Scheme 264

1. Raise the vehicle. For additional information, refer to «JACKING & HOISTING»(ref-232595-S06496072622006051700000) .
2. Remove the screws and remove the splash shield.
3. Detach the ambient air temperature sensor and disconnect the electrical connector.
4. To install, reverse the removal procedure.

Scheme 265

Scheme 266

1. Remove the instrument panel upper finish panel. Raise the upper finish panel. Disconnect the connector and remove the instrument panel finish panel.
2. Remove the dual sunload sensor. Disconnect the connector. Remove the dual sunload sensor.
3. To install, reverse the removal procedure.

Scheme 267

1. Remove the instrument cluster finish panel bezel. For additional information, refer to «INSTRUMENT PANEL AND CONSOLE»(ref-204638) .
2. Remove the in-car air temperature sensor. Disconnect the connector. Disconnect the aspirator hose and remove the in-car air temperature sensor.
3. To install, reverse the removal procedure.