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Home >> Mercury >> 1998 >> Sable V6-3.0L DOHC VIN S >> Repair and Diagnosis >> Heating and Air Conditioning >> Description and Operation >> Electronic Climate Control

Electronic Climate Control

The Electronic Automatic Temperature Control (EATC) system is available as an option on these vehicles.

The EATC uses the Integrated Control Panel (ICP) as the driver's interface to the system. The ICP communicates with the Remote Climate Control (RCC) module via the Audio Corporate Protocol (ACP) communication network. The RCC module controls all of the EATC hardware.

With the use of a microcomputer, the remote climate control module analyzes inputs from the following major sources:
- set temperature, function and blower speed selections (made by the vehicle occupants)
- in-car temperature sensor
- ambient temperature sensor
- A/C sunload sensor







Using these inputs, the remote climate control module microcomputer determines the correct conditions for the following six outputs:
- A/C clutch engagement request to powertrain control module
- blower speed
- A/C air temperature control door position
- heater air damper door position
- windshield defroster door position
- heater and A/C air inlet duct door position

An A/C electronic blend door actuator is used to operate the A/C air temperature control door.
- Vacuum control motors are used to control each of the three remaining air distribution doors.
- A feedback circuit is used in the A/C electronic blend door actuator to supply the control assembly with A/C air temperature control door position information.
- The blower motor is controlled by the control assembly through the A/C blower motor speed control.







- The A/C blower motor speed control reacts to the low power signal from the control assembly to provide the high power signal required to drive the blower motor The above system response chart shows the control assembly response to the function selections.

An on-board diagnostics feature has been included in the control assembly to supply the technician with Diagnostic Trouble Codes (DTCs). These DTCs direct the technician to the inoperative component.







SYSTEM OPERATION
The electronic automatic temperature control system automatically maintains the temperature selected for driving comfort and regulates the airflow between the:
- A/C registers.
- heater outlet floor ducts.
- windshield defroster hose nozzle.
- A/C side window demister and hoses.

The electronic automatic temperature control system has the following features:
- The system provides the option of manually overriding the blower speed and/or airflow direction.
- Additionally, the system has an A/C sunload sensor for automatic solar sensitivity, resulting in temperature compensation during high sunload conditions.
- The outside temperature can also be displayed at any time by momentarily pressing the OUTSIDE TEMP button. The outside temperature will then be displayed until the OUTSIDE TEMP or any other button is pressed.
- For optimum operation, the system should be in AUTO mode and set to the desired temperature setting.
- If the passenger compartment temperature is warmer or cooler than the set temperature, the climate control system will automatically provide heat (when the engine is warm) or air conditioning, as required, to reach the comfort setting as fast as possible.
- If it is necessary to adjust the comfort setting, the setting should be changed only in small increments (1-2 degrees) to maintain comfort and to avoid large variations of the passenger compartment temperature. Raising or lowering the set temperature in large increments from the comfort setting will not reduce the time required to reach stabilized comfort.

AUTO
The AUTO button functions in the following manner:
- Pressing the button turns the system on for fully automatic operation.
- The display window will be backlighted to show the selected temperature and AUTO.
- The system maintains the selected temperature by:
- controlling the airflow direction (functional setting).
- controlling airflow quantity (blower speed).
- controlling the discharge temperature required for comfort with the A/C air temperature control door.
- When heating is required, airflow will automatically be directed through the heater outlet floor ducts and A/C side window demister and hose with a small amount of air through the windshield defroster hose nozzles.
- During cool weather, the A/C blower motor operation will be delayed until the engine has heated sufficiently (about 49°C [120°F] engine coolant temperature) or for 3-1/2 minutes, whichever occurs first, to provide warm discharge temperatures.
- The airflow will be directed through the instrument panel A/C registers when cooling is required.
- The A/C registers can be adjusted for comfort. When maximum cooling is required, the system will automatically operate using recirculated air for rapid cool-down and automatically change to outside air as vehicle interior temperature approaches the selected temperature.
- In moderate conditions, the system will automatically operate with airflow directed through the heater outlet floor ducts and through the windshield defroster hose nozzles at a moderate A/C blower motor speed.

OFF
Pressing the OFF button:
- will turn the system off completely.
- leaves the digital display window blank unless OUTSIDE TEMP is selected.

Digital Display Window
The digital display window will indicate one of two displays depending upon the manual selection.
- selected function and comfort temperature
- outside temperature

TEMP
The TEMP button, used to raise or lower the temperature setting, operates as follows:
- Rocking the button once to the right will raise the temperature one degree.
- Holding the button in continuously to the right will raise the temperature setting in one-degree increments to 29°C (85°F) and then will jump to 32°C (90°F) in one step for continuous maximum heating.
- Rocking the button once to the left will lower the temperature one degree.
- Holding the button in continuously to the left will reduce the temperature setting in one-degree increments to 18°C (65°F) and then will jump to 16°C (60°F) in one step for continuous maximum cooling.

OUTSIDE TEMP
Pressing the OUTSIDE TEMP button will display the outside temperature until the OUTSIDE TEMP or any other button is pressed.
- If the system is turned OFF with the outside temperature selected or if the OUTSIDE TEMP button is pressed after the system is off, the outside temperature will be displayed in the digital display window for four seconds.

Manual Overrides
There are six manual override buttons along the lower edge of the integrated control panel. Each affects system operation as follows:

MAX A/C
Pressing the MAX A/C button will show MAX A/C and the set temperature in the display window.
- Heater and A/C air inlet duct door will close to outside air, allowing air from inside the vehicle to be drawn into the system.
- The A/C clutch will operate if the ambient temperature is approximately 10°C (50°F) or above.

VENT
Pressing the VENT icon button will show the VENT icon and the set temperature in the display window.
- The system will operate with outside air in the vent function.
- The A/C clutch will be turned OFF.

PANEL & FLOOR
Pressing the PANEL & FLOOR icon button will show the PANEL & FLOOR icon and the set temperature in the display window.
- The system will distribute outside air equally between the A/C registers and the heater outlet floor duct with a small bleed to the A/C side window demister and hose and the windshield defroster hose nozzle.
- The A/C clutch will operate if the ambient temperature is approximately 10°C (50°F) and above.

FLOOR
Pressing the FLOOR icon button will show the FLOOR icon and the set temperature in the display window.
- The system will distribute outside air through the heater outlet floor duct with a small bleed to the A/C side window demister and hoses and the windshield defroster hose nozzle.
- The A/C clutch will be turned OFF.

FLOOR & DEFROST
Pressing the FLOOR & DEFROST icon button will show the FLOOR and DEFROST icons and set temperature in the display window.
- The system distributes outside air equally between the windshield defroster hose nozzle and the heater outlet floor duct, with a small bleed out the A/C side window demister and hoses.
- The A/C clutch will operate if the ambient temperature is approximately 10°C (50°F) and above.

F-DEF
Pressing the F-DEF icon button will show the F-DEF icon and set temperature in the display window.
- The system distributes outside air to the windshield defroster hose nozzle and the heater outlet floor duct, with a small bleed to the heater outlet floor ducts.
- The A/C clutch will operate if the ambient temperature is approximately 10°C (50°F) and above.

-FAN+
The -FAN+ rocker switch is used to turn OFF the AUTOMATIC blower indicator and provide manual control of the A/C blower motor speed.
- The display will show FAN and a fan symbol.
- Rock the button to the left and hold to lock the blower motor at its lowest speed.
- Rock the button to the right and hold to lock the blower motor at its highest speed.

Press the AUTO button to resume automatic A/C blower motor control and remove FAN and the fan symbol from the display window.
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