A/c-Heater System - Automatic Mercury Sable II

SPECIFICATIONS

SPECIFICATIONS

Note. Systems using R-134a refrigerant are equipped with special identifying tags on A/C system components and refrigerant lines. System also uses a Gold colored A/C compressor clutch and Green "O" rings throughout.

DESCRIPTION

Electronic Automatic Temperature Control (EATC) system maintains selected in-vehicle temperature. The EATC control panel uses a microcomputer to analyze input from temperature/blower motor speed selection, passenger compartment temperature, ambient temperature, engine temperature and sunload. System has a self-diagnostics feature in which error codes are stored in the microprocessor memory and displayed on EATC control panel.

Microcomputer determines A/C compressor clutch engagement, blower speed, blend door position, floor/panel door position, panel/defrost door position and fresh/recirculated air door position. A small electric motor is used to operate temperature blend door, and vacuum actuators are used to control remaining air distribution doors. A feedback circuit is used with blend door actuator, enabling microcomputer to identify door position.

EATC CONTROL PANEL

The EATC control panel consists of a digital display to show set temperature, temperature and mode control buttons, and a blower speed control thumb wheel. The temperature can be increased with the WARMER button (Red) up to 85° F (29° C) or decreased with the COOLER button (Blue) down to 65°F (18°C). Trouble codes can be displayed on the digital display by simultaneously pushing OFF and FLOOR, then AUTOMATIC button within 2 seconds. (Scheme 1)

MODE BUTTONS

The 6 mode buttons on the lower edge of EATC control panel override automatic function. (Scheme 1) The override buttons affect system operation as follows

MAX A/C

Pressing MAX A/C button will display "60°F MAX A/C" in display window. Blower will go to high and recirculation function will be activated.

VENT

Pressing vent button will display "VENT" in the display window. The system will operate with A/C compressor off, and circulate outside air to the panel vents.

PNL-FLR

Pressing PNL-FLR will show "PANEL FLOOR" in the display window. Air will be equally distributed between panel and floor vents.

FLOOR

Pressing FLOOR button will display "FLOOR" in the display window. Most air will be directed to floor ducts, with a small amount going to the window demister and defrost vents.

FLR-DEF

Pressing FLR-DEF button will show "FLOOR DEFROST" in the display window. Most air will be directed to floor and defrost vents, with a small amount of air going to side window demisters.

Defrost

Pressing defrost button lights defrost indicator. Most air will be directed to defroster vents, with a small amount going to floor ducts and side window demisters.

Scheme 1

Ambient Temperature Sensor

Sensor contains a thermistor (temperature sensitive resistor), which measures outside air temperature and inputs signal to EATC control panel. Ambient temperature sensor is located in front of condenser, on radiator support.

In-Vehicle Temperature Sensor

Sensor contains a thermistor (temperature sensitive resistor), which measures temperature inside vehicle and inputs signal to EATC control panel. In-vehicle sensor is located behind instrument panel, above glove box.

Sunload Sensor

Sunload sensor contains a photovoltaic (sunlight sensitive) diode, which measures sunlight entering vehicle and inputs signal to EATC control panel. Sensor is located on upper right instrument panel.

Blower Thumbwheel

Rotating blower thumbwheel more than 10 degrees will provide manual control of blower speed. Rotating thumbwheel fully downward will lock blower speed in slowest speed. Rotating thumbwheel fully upward will lock blower speed in fastest speed. Pushing AUTOMATIC button will resume automatic operation.

Blower Speed Controller

Blower speed controller is located in the evaporator case, upstream of evaporator core. The controller converts low current signals from EATC control panel to a high current, variable ground feed to the blower motor. Blower motor speed is controlled by EATC control panel and blend door actuator position.

A delay function provides gradual increases or decreases in blower motor speeds. High-speed blower relay, integral with blower speed controller, gives maximum airflow in high blower position.

Note. Do not operate system with blower motor disconnected, or blower speed controller may be damaged.

Cold Engine Lock-Out (CELO) Switch

This switch prevents blower operation when engine coolant temperature is less than 120°F (49°C). CELO will not prevent blower operation when A/C or defrost is selected. CELO is located in heater hose, before heater core.

TEMPERATURE BLEND DOOR ACTUATOR

Temperature blend door is operated by an electric motor (actuator). The actuator has an automatic recalibrating feature that can be activated by disconnecting positive battery cable from battery for at least 30 seconds. When positive cable is reconnected, system will automatically recalibrate.

PRESSURE RELIEF VALVE

This valve relieves high-side pressure build-up above 450 psi (31.6 kg/cm 2 ), and prevents damage to A/C compressor and other system components. Pressure relief valve is located on side of high-pressure line, near compressor manifold.

VACUUM ACTUATORS

Three vacuum actuators control movement of air distribution doors. Two of the vacuum actuators are mounted on plenum. One vacuum actuator controls movement of the floor/panel door. A second vacuum actuator is used for panel/defrost door.

The third vacuum actuator is mounted on the fresh/recirculated air duct, and controls movement of the fresh/recirculated air door.

A/C Compressor Clutch

In any mode in which the A/C compressor clutch operates, the compressor clutch (signal) is controlled by Constant Control Relay Module (CCRM). CCRM is located in front of engine compartment, on upper radiator support. The Powertrain Control Module (PCM) will override the EATC control panel commands and disengage the compressor clutch during wide open throttle acceleration.

Clutch Cycling Pressure Switch

This pressure-sensitive switch controls the compressor clutch circuit based on evaporator core pressure. The switch controls evaporator core temperature to prevent evaporator icing. Switch opens when suction pressure is 22-28 psi (1.5-2.0 kg/cm 2 ), and switch closes when suction pressure rises to about 40-47 psi (2.8-3.3 kg/cm 2 ).

AIR BAG WARNING

Preliminary Information & Test Sequence

1. Perform «EATC SELF-DIAGNOSTIC TEST»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__eatc-self-diagnostic-test) . Record all error codes displayed during self-test. If error codes appear, follow diagnostic procedures outlined for each error code recorded.
2. If a malfunction exists but no error code appears, follow procedures outlined in «EATC SYSTEM FUNCTIONAL TEST»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__eatc-system-functional-test) and «DIAGNOSIS WHEN EATC SELF-DIAGNOSTICS INDICATE NO ERRORS FOUND»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__diagnosis-when-eatc-self-diagnostics-indicate-no) . These procedures detect system failures self-test cannot.

EATC SELF-DIAGNOSTIC TEST

Note. Coolant temperature must be at least 120°F (49°C) before entering self-diagnostics.

Entering Self-Diagnostics

1. Simultaneously depress OFF and FLOOR buttons, then press AUTOMATIC button within 2 seconds. Display will be blank for up to 20 seconds while test is running.
2. If display is blank for more than 20 seconds, go to «DIAGNOSIS WHEN EATC SELF-DIAGNOSTICS INDICATE NO ERRORS FOUND»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__diagnosis-when-eatc-self-diagnostics-indicate-no) . If codes are displayed, repair all error codes in order, from lowest number to highest number. See ERROR CODE DIAGNOSIS.
3. Self-diagnostics can be initiated at any time with the resulting error codes being displayed. Normal system operation is stopped when system is in self-diagnostic mode.

Exiting Self-Diagnostics

To exit self-diagnostics, depress COOLER button (Blue). (Scheme 1) Deactivate self-diagnostics before turning system off.

Error Code 01 (Control Panel Problem)

If Code 01 appears, replace EATC control panel. See EATC CONTROL PANEL under REMOVAL & INSTALLATION.

Error Code 02 (Blend Door Problem)

1. Unplug both EATC control panel connectors. Check blend door actuator movement. Turn ignition on, with engine off.
2. On 8-pin connector, attach a jumper wire from Black wire to Dark Blue/Light Green wire. See «WIRING DIAGRAMS»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) . Blend door should move. Disconnect jumper wire from Dark Blue/Light Green wire, and connect to Orange wire terminal. Blend door should move in other direction.
3. If blend door actuator does not operate in both directions, proceed to next step. If actuator operates in both directions, plug in EATC control panel connectors and retest system. See «EATC SYSTEM FUNCTIONAL TEST»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__eatc-system-functional-test) . If test is successful (no Code 02), test is complete.
4. If blend door actuator did not move in step 3), check blend door feedback potentiometer. Turn ignition off. Measure resistance between specified wire terminals on 12-pin EATC control panel connector. See «BLEND DOOR FEEDBACK POTENTIOMETER TEST»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) table.
5. If resistances in step 4) are okay, replace EATC control panel. Check system function using «EATC SYSTEM FUNCTIONAL TEST»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__eatc-system-functional-test) . If resistances were not correct, go to next step.
6. Unplug both EATC control panel connectors and blend door actuator connector. Check wiring between EATC control panel and blend door actuator for continuity and short circuits. See «WIRING DIAGRAMS»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) .
7. If continuity checks are not okay in step 6), repair or replace wiring harness. If continuity checks are okay, replace blend door actuator. Retest system. See «EATC SYSTEM FUNCTIONAL TEST»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__eatc-system-functional-test) .

BLEND DOOR FEEDBACK POTENTIOMETER TEST (1)

Error Code 03 (In-Car Temperature Sensor)

1. Symptoms associated with Code 03 are cold air discharged when heat is selected and warm air discharged when A/C is selected. Unplug in-car temperature sensor. Measure resistance across sensor terminals. See «IN-CAR & AMBIENT TEMPERATURE SENSOR RESISTANCE»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) table.
2. If sensor resistance is not as specified, replace sensor. If sensor resistance is okay, disconnect negative battery cable. Check wiring and connectors between sensor and EATC control panel for shorts or open circuits. See «WIRING DIAGRAMS»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) . Repair as necessary.

IN-CAR & AMBIENT TEMPERATURE SENSOR RESISTANCE

Error Code 04 (Ambient Temperature Sensor)

1. Symptoms associated with Code 04 are outside temperature display reads "-40°" or "140°". Also, check for cold air discharged when heat is selected or warm air discharged when A/C is selected.
2. Disconnect negative battery cable to reset outside temperature display. Unplug wiring harness at ambient temperature sensor. Measure resistance across sensor terminals. See «IN-CAR & AMBIENT TEMPERATURE SENSOR RESISTANCE»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) table.
3. Replace sensor if resistance is not as specified. If resistance is okay, keep battery cable disconnected. Unplug connectors from EATC control panel. Check wiring and connectors between ambient temperature sensor and EATC control panel for shorts or open circuits. See «WIRING DIAGRAMS»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) . Repair as necessary.

Error Code 05 (Sunload Sensor)

1. Disconnect negative battery cable. Unplug wiring harness connectors at sunload sensor and EATC control panel. Check wiring and connectors for continuity, shorts and opens. See «WIRING DIAGRAMS»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) . Repair as necessary.
2. Sensor is a photodiode and can be checked with an ohmmeter. With harness disconnected, there should be some unspecified resistance present across sensor terminals, depending on amount of light available. If resistance is zero ohms, replace sensor.

Error Code 888 (No Fault Found)

If Code 888 appears, perform EATC SYSTEM FUNCTIONAL TEST .

EATC SYSTEM FUNCTIONAL TEST

Note. Perform this test if EATC SELF-DIAGNOSTIC TEST showed no error codes and fault is present.

1. Ensure engine is cold and in-vehicle temperature is greater than 50°F (10°C). Turn ignition on. Press AUTOMATIC button and set temperature display to 90°F. If EATC control panel lights, go to next step. If EATC control panel does not light, go to «DIAGNOSIS WHEN EATC SELF-DIAGNOSTICS INDICATE NO ERRORS FOUND»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__diagnosis-when-eatc-self-diagnostics-indicate-no) .
2. Verify blower motor does not come on with engine temperature less than 120°F (49°C). If blower motor does not come on, go to next step. If blower motor comes on, go to «COLD ENGINE LOCK-OUT SWITCH INOPERATIVE»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__cold-engine-lock-out-switch-inoperative) test under «BLOWER SPEED CONTROLLER & HIGH-SPEED BLOWER RELAY»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) .
3. Start engine. Ensure coolant temperature is greater than 120°F (49°C). Set temperature display to 75°F. If blower motor comes on, go to next step. If blower motor does not come on, go to NO BLOWER test under «BLOWER SPEED CONTROLLER & HIGH-SPEED BLOWER RELAY»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) .
4. Rotate blower speed knob fully down. If blower motor goes to low speed, go to next step. If blower motor does not go to low speed, go to NO BLOWER test under «BLOWER SPEED CONTROLLER & HIGH-SPEED BLOWER RELAY»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) . NOTE: Before going to step 5), check battery voltage. If voltage reading is less than 10 volts, check charging system.
5. Rotate blower knob fully up. If blower motor goes to high speed, go to next step. If blower motor does not go to high speed, go to «BLOWER SPEED CONTROLLER & HIGH-SPEED BLOWER RELAY»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) .
6. Press defrost button. Verify air is discharged from defroster nozzle with a small amount of air bleed through side window demisters. Also, verify fresh/recirculated air door is in fresh air position. If air discharge and fresh/recirculated air door position is correct, go to next step. If air is not discharged through defroster or side window demisters, go to «VACUUM SYSTEM TEST»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__vacuum-system-test) .
7. Press FLOOR button. If air is discharged through floor air ducts, go to next step. If air discharge is not through floor air ducts, go to «VACUUM SYSTEM TEST»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__vacuum-system-test) .
8. Press VENT button. If air discharge is through panel ducts, go to next step. If air discharge is not through panel ducts, go to «VACUUM SYSTEM TEST»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__vacuum-system-test) .
9. Ensure ambient temperature is more than 40°F (4°C). Press MAXA/C button. If fresh/recirculated air door is in recirculated air position, go to next step. If door is not in recirculated air position, go to «VACUUM SYSTEM TEST»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__vacuum-system-test) .
10. Press VENT button. If VENT display is lit and A/C compressor clutch turns off, go to next step. If A/C compressor clutch remains on, go to «A/C COMPRESSOR CLUTCH DOES NOT DISENGAGE WHEN IN OFF POSITION»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__ac-compressor-clutch-does-not-disengage) .
11. Press MAX A/C button again. If MAX A/C lights up and A/C compressor clutch comes on, go to next step. If A/C compressor clutch remains off, go to «NO A/C COMPRESSOR CLUTCH OPERATION»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__no-ac-compressor-clutch-operation) .
12. Press AUTOMATIC button. If AUTOMATIC button lights, test is complete. If AUTOMATIC button does not light, go to «DIAGNOSIS WHEN EATC SELF-DIAGNOSTICS INDICATE NO ERRORS FOUND»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic__diagnosis-when-eatc-self-diagnostics-indicate-no) .

DIAGNOSIS WHEN EATC SELF-DIAGNOSTICS INDICATE NO ERRORS FOUND

Note. If self-diagnostics and EATC SYSTEM FUNCTIONAL TEST does not locate problem, refer to symptoms listed. Perform outlined test procedures or service as required.

Cool Air Discharge With System Set At 90°F In AUTOMATIC Mode

Check coolant level and heater system for possible malfunction. Check blend door shaft attachment, door position and blend door actuator. Blend door may not be in maximum heating position. To test blend door actuator, see ERROR CODE 02 under ERROR CODE DIAGNOSIS.

Warm Air Discharge With System Set At 60°F In AUTOMATIC Mode

Check refrigerant level and A/C compressor clutch engagement. See NO A/C COMPRESSOR CLUTCH OPERATION . Check blend door shaft attachment, door position and blend door actuator. Blend door may not be in maximum cooling position. Fresh/recirculated air door may not be in recirculation position. To test blend door actuator, see ERROR CODE 02 under ERROR CODE DIAGNOSIS. Check vacuum system. See VACUUM SYSTEM TEST .

Cool Air Discharge In 85°F & Maximum Heat In 90°F

Check for shorted sensor or wiring. See ERROR CODE DIAGNOSIS . Replace sensor or repair wiring.

Heated Air Discharge In 65°F & Cool Air Discharge In 60°F

Check for open sensor or wiring. See ERROR CODE DIAGNOSIS . Replace sensor or repair wiring.

No Blower

Faulty cold engine lock-out switch. See NO BLOWER under BLOWER SPEED CONTROLLER & HIGH-SPEED BLOWER RELAY . Check wiring, blower motor, blower speed controller or EATC control panel for possible malfunction.

Blower Operates In High Speed Only

See BLOWER OPERATES IN HIGH-SPEED ONLY under BLOWER SPEED CONTROLLER & HIGH-SPEED BLOWER RELAY . Check wiring or blower speed controller for possible malfunction.

A/C Compressor Clutch Engaged In OFF Position

See A/C COMPRESSOR CLUTCH DOES NOT DISENGAGE WHEN IN OFF POSITION . Check wiring or components for possible malfunction.

Control Panel Digital Display Does Not Light (Blower Off)

Check fuses. Check for open battery and ignition circuits to EATC control panel. Check for open ground circuit to EATC control panel. EATC Control panel is grounded at left front side of engine compartment, at radiator support. Defective EATC control panel. Repair or replace as necessary.

Cold Air Delivered During Heating With Engine Cold

1. Check cold engine lock-out (engine coolant temperature) switch for damage. Replace if necessary. If switch is okay, press AUTOMATIC button and set temperature display to 90°F.
2. With ignition off, ground Yellow/White wire at cold engine lock-out switch. Switch is located in-line in heater hose.
3. Start vehicle. If blower motor is off, replace cold engine lock-out switch. If blower motor comes on, check wiring. See «WIRING DIAGRAMS»(/mercury/sable/ii-1991-1995/remont/automatic-hvac-system/#ac-heater-system-automatic) . If wiring is okay, replace EATC control panel. CAUTION: Exercise caution when testing English/Metric circuit. Accidentally shorting wrong pin can damage EATC control panel.

Temperature Display Does Not Switch From Fahrenheit To Celsius

Short pin No. 20 (Red wire) of EATC control panel 12-pin connector to ground. See WIRING DIAGRAMS . Turn ignition on with engine off. If display does not switch from Fahrenheit to Celsius, Red wire is open at EATC control panel or EATC control panel is damaged. Also check wiring and trip minder.

System Does Not Control Temperature

In-car temperature sensor hose disconnected or damaged, sensor seals missing or improperly installed, aspirator not secured to evaporator case. Repair or replace as necessary.

EATC Control Panel Turns On & Off Erratically With No System Control

Check for faulty charging system. EATC will not function with too low or too high battery voltage. Check battery voltage. If battery voltage is less than 10 volts or more than 16 volts, a charging system problem exists. DO NOT replace EATC control panel. Repair charging system.

NO A/C COMPRESSOR CLUTCH OPERATION

1. Check for low refrigerant charge. Recharge A/C system as necessary. Unplug A/C compressor clutch coil connector at coil. Battery voltage should be present in any mode in which A/C clutch should be operating. If battery voltage is present, but clutch does not engage, replace clutch coil.
2. If battery voltage is not present, jump compressor clutch cycling switch harness terminals. If clutch engages, check cycling switch. Switch opens when suction pressure is about 22 psi (1.5 kg/cm 2 ), and closes when suction pressure rises to about 45 psi (3 kg/cm 2 ). Replace switch if faulty.
3. If compressor clutch does not engage, check wiring to EATC control panel, integrated relay control module and A/C clutch diode. Fault may be in PCM system. PCM interrupts A/C compressor clutch during wide open throttle.

A/C COMPRESSOR CLUTCH DOES NOT DISENGAGE WHEN IN OFF POSITION

Note. For EEC-IV system testing, see appropriate ENGINE PERFORMANCE article in the ENGINE PERFORMANCE Section.

Unplug 8-pin EATC control panel connector. If A/C compressor clutch disengages, replace EATC control panel. If A/C compressor clutch stays on, check wiring, cycling clutch pressure switch, integrated relay control module or EEC-IV module.

1. Ensure ignition switch is in RUN position, system is in AUTOMATIC mode and display is in 90°F setting.
2. Change temperature setting to 60°F. If blower does not come on, go to next step. If blower motor comes on, disconnect Cold Engine Lock-Out (CELO) switch, located in heater hose before heater core. Change temperature setting to 90°F. If blower motor comes on, replace faulty CELO switch. If blower motor remains off, CELO switch wiring is shorted to ground. Repair wiring as necessary.
3. Connect digital voltmeter between blower speed controller Light Blue/Pink wire (White/Purple wire on Continental) and Black (ground) wire. If reading is zero volts, check fuse and circuit wiring through high-speed blower relay. If reading is more than 10 volts, go to next step.
4. Connect digital voltmeter between blower speed controller Tan/Orange wire and Black (ground) wire. If reading fluctuates at less than 3 volts, go to next step. If reading fluctuates at more than 3 volts, go to step 6).
5. Connect digital voltmeter between blower speed controller Orange/Red wire and Black (ground) wire. If reading is more than one volt, replace blower speed controller. If reading is less than one volt, check for battery feed to blower motor or faulty motor.
6. Connect digital voltmeter between EATC control panel pin No. 23 (Tan/Orange wire) and No. 24 (Black wire). If reading is more than 3 volts, replace EATC control panel. If reading is less than 3 volts, check circuit wiring through high-speed blower relay.

1. Unplug blower speed controller connector. If blower motor continues to operate in high-speed, wiring or blower motor is defective (shorted). If blower motor turns off, go to next step.
2. Reconnect blower speed controller connector. Connect digital voltmeter between blower speed controller Tan/Orange wire and Black (ground) wire.
3. Place system in AUTOMATIC mode, and rotate blower switch from high to low. If reading fluctuates at less than 7 volts, replace EATC control panel. If reading fluctuates at more than 7 volts, replace blower speed controller.

Cold Engine Lock-Out Switch Inoperative

1. Ensure coolant temperature is less than 120°F (49°C), system is in AUTOMATIC mode and temperature set to 90°F. If blower motor comes on, check coolant temperature and retest.
2. If blower motor comes on with engine cold, replace cold engine lock-out (engine coolant temperature) switch. If blower motor is off, cold engine lock-out switch is okay.

Blower Operates But Does Not Vary With Blower Control Switch

1. Connect digital voltmeter between blower speed controller Tan/Orange wire and Black (ground) wire. Place system in AUTOMATIC mode, and rotate blower switch from low to high and back to low.
2. If reading fluctuates, go to next step. If reading does not fluctuate, replace EATC control panel.
3. Connect digital voltmeter between blower speed controller Orange/Red wire and Black wire. Place system in AUTOMATIC mode and rotate blower switch from low to high.
4. If reading fluctuates, check for battery feed voltage to blower motor or faulty motor. If voltmeter reading does not change, replace blower speed controller.

VACUUM SYSTEM TEST

Note. A continuous hiss at EATC control panel indicates a major vacuum leak somewhere in system. It does not necessarily indicate leak is at EATC control panel.

Scheme 2

1. Start engine and depress EATC control panel function buttons slowly from one position to another. A momentary hiss should be heard as each button is pressed. Hissing indicates vacuum is available at EATC control panel.
2. If hiss is not heard, check for a kinked, pinched or disconnected vacuum supply hose. Also, inspect check valve between intake manifold and vacuum reservoir to ensure it is working properly.
3. If momentary hiss is heard as each function button is pressed, vacuum is available at EATC control panel. Cycle function buttons through each position with blower on high position, and check air discharge at ducts.
4. If a vacuum motor fails to operate, airflow at ducts will be incorrect. (Scheme 2) If vacuum motor is inoperative, apply vacuum to motor. If motor operates, check vacuum hose (going to motor) for leaks or disconnection.
5. If vacuum system works normally at idle, but goes to defrost during acceleration, a small leak exists in vacuum system. Locate leak by shutting engine off and using a vacuum gauge to check for vacuum loss, while selectively blocking off vacuum hoses. Check in-line check valve.

Removal (Continental & Taurus 3.8L)

1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect negative battery cable. Disconnect and remove integrated relay controller. Remove fan shroud assembly, radiator hose and radiator.
2. Disconnect A/C compressor clutch wiring. Raise vehicle on hoist. Loosen and remove compressor drive belt. Disconnect oxygen sensor wiring. Remove A/C muffler support strap bolt from frame.
3. Disconnect refrigerant lines from condenser and receiver-drier. Cap all openings. Support compressor and remove compressor mounting bolts. Remove compressor, manifold and tubes as an assembly. Remove manifold, tubes and clutch from compressor.

Installation

To install, reverse removal procedure. Before installing new compressor, ensure 3 ozs. of clean refrigerant oil is installed in new compressor. Evacuate and recharge A/C system.

Removal (Sable & Taurus Except 3.8L)

1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect A/C compressor clutch wiring. Loosen drive belt. Disconnect hoses from condenser and suction line. Cap all openings.
2. Remove 4 compressor mounting bolts. From top of vehicle, remove compressor, manifold and tubes as an assembly. Remove manifold, tubes and clutch from compressor.

To install, reverse removal procedure. Before installing new compressor, ensure 3 ozs. of clean refrigerant oil is installed in new compressor. Evacuate and recharge A/C system.

Removal & Installation

1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect suction line from compressor. Disconnect inlet tube from evaporator core outlet. Cap all openings to keep moisture out.
2. Disconnect pressure switch connector on top of receiver-drier. Remove mounting screw and receiver-drier. To install, reverse removal procedure. Evacuate and recharge A/C system.

Removal & Installation (Continental)

1. Disconnect positive battery cable.
2. Remove right side finish molding by pulling upward to unsnap six clips and disconnect wiring. (Scheme 3)
3. Open glove compartment door and depress sides inward and lower glove compartment assembly toward floor.
4. Remove left side finish molding by pulling upward to unsnap two clips. (Scheme 3)
5. Remove four push pins from right side and left side lower insulators. Remove insulators. (Scheme 4)
6. Remove five screws retaining lower instrument panel steering column cover and remove cover.
7. Remove four screws retaining lower instrument panel steering column reinforcement. Remove reinforcement.
8. Remove four retaining nuts and absorber assembly.
9. Remove four screws retaining upper steering column shroud and remove. (Scheme 5)
10. Remove tilt/wheel lever. (Scheme 6)
11. Remove lock cylinder by pushing a small Allen wrench into groove located beneath lock cylinder. Place key into ignition and gently wiggle to work cylinder free. (Scheme 6)
12. Remove lower steering column shroud by pulling out. (Scheme 6)
13. Remove bolt retaining PRNDL cable to steering column. (Scheme 6)
14. Disconnect all electrical connectors. (Scheme 6)
15. Disconnect hood and brake release cables.
16. Remove four nuts retaining steering column. Lower steering column. (Scheme 7)
17. Remove screw at steering column opening, retaining instrument panel to brake pedal support.
18. Remove two screws under ash receptacle which retains instrument panel to A/C plenum case. (Scheme 8)
19. Remove headlamp switch knob.
20. Remove five screws from cluster opening finish panel and remove panel. (Scheme 3).
21. Remove four screws retaining A/C control. Disconnect electrical connectors and one vacuum connector. (Scheme 9)
22. Remove four screws retaining cluster. Disconnect electrical connectors. (Scheme 10)
23. Remove three screws to remove glove compartment assembly. (Scheme 11)
24. Remove two screws from instrument panel to cowl top brace and one screw from passenger air bag support bracket. (Scheme 8)
25. Remove both speaker grilles by snapping out to release.
26. Remove two screws and remove center defrost grille. (Scheme 3)
27. Under the hood, disconnect all electrical connectors of main wire loom. (Scheme 3)
28. Disengage rubber grommet from dash panel and feed wiring and connectors through hole into instrument panel area. (Scheme 3)
29. Remove three screws (two on sill plate) at both right hand and left hand cowl trim panels. Remove panels. (Scheme 3)
30. Disconnect wiring at right hand and left hand cowl side panels. (Scheme 3)
31. Remove lower two screws at instrument panel, one at each end. (Scheme 3)
32. Remove three upper instrument panel retaining screws and carefully lower instrument panel. Disconnect all electrical and vacuum connectors. Remove instrument panel from vehicle. (Scheme 3)
33. To install instrument panel, reverse removal procedure.
34. Check air bag indicator operation. See «SYSTEM OPERATION CHECK»(/mercury/sable/ii-1991-1995/remont/airbag/#air-bag-restraint-system__system-operation-check) in AIR BAG RESTRAINT SYSTEM article in RESTRAINTS.

Scheme 3

Scheme 4

Scheme 5

Scheme 6

Scheme 7

Scheme 8

Scheme 9

Scheme 10

Scheme 11

Removal & Installation (Sable & Taurus)

1. Position front wheels in straight-ahead position. Disconnect positive battery cable. Remove 4 steering column cover screws and cover. Remove sound insulator by removing nuts from studs on evaporator case. Remove steering column trim shrouds. Unplug connectors from steering column switches.
2. Remove radio trim panel and radio. Remove 4 steering column bracket mounting bolts. Lower steering column. Remove instrument cluster trim panel retaining screws. Release instrument cluster trim panel by rocking upper edge of panel toward driver's seat. Remove 4 instrument cluster retaining screws and remove instrument cluster. Remove one bolt at steering column opening and one bolt under radio opening.
3. Disconnect speedometer cable. Remove 3 bolts and glove box assembly. Remove air cleaner, battery and battery tray. Disconnect wiring harness on engine compartment side. Disengage rubber grommet from firewall. Feed main wiring harness and connectors through opening and into instrument panel area.
4. Remove right and left cowl side trim panels. Remove screws retaining instrument panel on left and right sides. Disconnect vacuum hoses, wiring harness, radio antenna cable and A/C-heater control cable by reaching through steering column, instrument cluster and glove box openings.
5. Snap out right/left speaker covers. Remove 3 upper and lower instrument panel retaining screws. Remove instrument panel. To install, reverse removal procedure.

EVAPORATOR CASE

Scheme 12

1. Disconnect negative battery cable. Drain cooling system. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect hoses from heater core. Plug heater core tubes and blow coolant from core. (Scheme 12)
2. Disconnect vacuum supply hose from in-line vacuum check valve in engine compartment. Disconnect liquid line and accumulator from evaporator core. Plug all openings.
3. Remove instrument panel. Remove instrument panel shake brace from evaporator case. Remove 2 screws attaching floor register or rear seat adapter to bottom of evaporator case.
4. Remove 3 nuts (in engine compartment) attaching evaporator case to firewall. Remove 2 support brackets-to-cowl top panel screws. Carefully pull evaporator case from firewall. To install, reverse removal procedure.

EVAPORATOR CORE

Removal

1. Remove evaporator case. See EVAPORATOR CASE under REMOVAL & INSTALLATION. Disconnect and remove vacuum harness. Remove 6 screws and recirculation duct from evaporator case. Remove 2 screws and air inlet duct from evaporator case.
2. Remove evaporator case support bracket. Remove connector bracket-to-recirculation duct screw. Disconnect high-speed blower relay lead from blower speed controller. (Scheme 12)
3. Release 3 connectors from bracket and remove bracket. Remove screws and high-speed blower relay. Remove 3 screws and blend door actuator. Remove cold engine lock-out switch from heater core tube.
4. Remove molded seals from evaporator core tubes. Drill a 3/16" hole in each of the 2 upright tabs on top of evaporator case. Using a small saw, cut top of evaporator case on 3 sides between raised outlines. (Scheme 13) Fold cutout back and remove evaporator core.

Scheme 13

1. Transfer core seals to new evaporator core. Install evaporator core into evaporator case. Install spring nut on both upright tabs. Install screws into spring nuts to secure cover.
2. Using Caulking Cord (D9AZ-19560-A), seal evaporator case along cut line. To install, reverse removal procedure. Fill cooling system and check for leaks. Evacuate, recharge and leak test A/C system.

1. Remove instrument panel and evaporator case. Remove vacuum line from heater core tube seal. Remove seal from heater core tubes. Remove 3 blend door actuator-to-evaporator case screws.
2. Remove actuator and cold engine lock-out switch from case. Remove 4 heater core access cover mounting screws, access cover, seal and heater core from evaporator case. To install, reverse removal procedure. Fill cooling system and check for leaks. Evacuate, recharge and leak test A/C system.

1. Open glove box, release retainers and lower door. Remove recirculation duct support bracket-to-cowl screw. Remove connector bracket-to-recirculation duct screw.
2. Release 3 connectors from bracket and remove bracket. Disconnect vacuum hose to recirculation door vacuum motor. Remove 6 recirculation duct-to-evaporator case screws.
3. Remove recirculation air duct from evaporator by lowering it between instrument panel and evaporator case. (Scheme 12) Unplug blower motor connector. Remove fan wheel push nut and fan wheel. Remove 4 screws and blower motor. To install, reverse removal procedure.

Lower glove box door to provide access to recirculation duct assembly. Disconnect vacuum hose from end of vacuum motor. Detach motor arm retainer from door crank arm. Remove nuts and vacuum motor. To install, reverse removal procedure.

Disconnect negative battery cable. Remove instrument panel. Detach vacuum motor arm from door shaft. Disconnect vacuum hose from actuator. Remove nuts and actuator. To install, reverse removal procedure.

1. Disconnect negative battery cable. Remove instrument cluster opening finish panel screws and finish. Pull lower edge of finish panel away from instrument panel.
2. Remove 4 EATC control panel-to-instrument panel screws. Slide control panel out from instrument panel opening. Disconnect wiring harness from back of EATC control panel. To install, reverse removal procedure.

Disconnect negative battery cable. Remove instrument panel snap-in finish inserts. Remove 8 screws retaining upper finish panel. Pull lower edge of upper finish panel away from instrument panel. Remove 4 Torx screws, and pull control assembly from instrument panel. Unplug electrical connections. To install, reverse removal procedure.

Disconnect negative battery cable. Remove trim panel on upper right side of instrument panel. Remove 2 sunload sensor mounting nuts. Unplug electrical connector. Remove sunload sensor. To install, reverse removal procedure.

Disengage instrument panel air duct assembly, located above glove box door. Sensor is located on back of air duct assembly, near center of its lower edge. Unplug connector and flexhose from sensor. Pull sensor from retainer. To install, reverse removal procedure.

Disconnect negative battery cable. Disengage glove box door tabs and let door hang. Remove temperature sensor from bracket attached to instrument panel. Disconnect harness connector from sensor. Disconnect aspirator hose from sensor. To install, reverse removal procedure.

Disconnect negative battery cable. Remove ambient sensor nut and sensor, located on condenser on right side of vehicle. Unplug electrical connector. To install, reverse removal procedure.

1. Disengage glove box door stops and allow door to hang by hinge. Working through glove box opening, unplug electrical connector and hose at blower speed controller. Free connector from its mounting bracket.
2. Remove blower speed controller-to-evaporator case screws. Disconnect snap lock connector and aspirator hose. Remove 2 screws and blower speed controller. To install, reverse removal procedure.

Unplug connector from switch, threaded into heater core inlet tube fitting in engine compartment. Partially drain coolant from radiator. Remove switch from fitting. To install, apply sealer to switch threads and install on fitting. Plug connector and add coolant to radiator.

1. Disconnect negative battery cable. Loosen instrument panel and pull back from cowl. Free blend door actuator connector from bracket on evaporator case.
2. Remove 3 actuator attaching screws and cold engine lock-out switch from heater core tube. Lift actuator vertically 1/2" to disengage it from bracket and blend door shaft. Pull actuator toward passenger compartment.

To install, reverse removal procedure. After actuator is installed, disconnect positive battery cable. After 30 seconds, reconnect cable to terminal. Actuator adjustment will be automatic.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

Automatic A/C-Heater System Wiring Diagram (Continental). Scheme 14

Auto A/C-Heater System Wiring Diagram (Sable & Taurus - 1 Of 4). Scheme 15

Auto A/C-Heater System Wiring Diagram (Sable & Taurus - 2 Of 4). Scheme 16

Auto A/C-Heater System Wiring Diagram (Sable & Taurus - 3 Of 4). Scheme 17

Auto A/C-Heater System Wiring Diagram (Sable & Taurus - 4 Of 4). Scheme 18

See also:
• SYSTEM OPERATION CHECK
• EATC SELF-DIAGNOSTIC TEST
• EATC SYSTEM FUNCTIONAL TEST
• DIAGNOSIS WHEN EATC SELF-DIAGNOSTICS INDICATE NO ERRORS FOUND
• EATC CONTROL PANEL
• COLD ENGINE LOCK-OUT SWITCH INOPERATIVE
• VACUUM SYSTEM TEST
• A/C COMPRESSOR CLUTCH DOES NOT DISENGAGE WHEN IN OFF POSITION
• NO A/C COMPRESSOR CLUTCH OPERATION
• ERROR CODE 02