A/c-Heater System - Automatic Lincoln Continental VII

DESCRIPTION

Electronic ATC is used on Mark VII and Continental. The control assembly uses a microcomputer to analyze 4 major inputs: temperature and mode selection, in-vehicle temperature, ambient temperature and engine temperature. The microcomputer determines the conditions for 6 control outputs: A/C compressor clutch engagement, blower speed, blend door position, mode door position, panel defrost door position, and fresh air/recirculation door position.

Small DC electric motors are used to operate 4 air doors. (Scheme 1) A feedback circuit is used in each motor so that the computer can identify the door's position. A/C compressor clutch and blower motor are controlled through the blower speed controller (BSC).

System Block Diagram. Scheme 1

CONTROL PANEL

The Electronic ATC control panel assembly consists of 9 mode push buttons, a vacuum fluorescent display (VFD) and 7 light emitting diodes (LEDs). The set temperature can be raised or lowered in one degree increments (between 65°F-85°F) through the use of "WARMER" or "COOLER" mode push buttons. The other 7 mode push buttons are "OFF", "ECON", "LO AUTO", "AUTO", "HI AUTO", "MIX" and "DEFROST". (Scheme 2)

The control panel assembly performs the following functions

Scheme 2

1. Processes data from the customer's input to the control panel, from in vehicle, ambient and engine temperature sensors and from 4 actuator position sensors.
2. When turned on, remembers temperature and mode selected before last shut-off.
3. Provides continuous position control of the blend and mode doors.
4. Provides 2-position control of the "PAN/DEF" and "FRESH AIR/REC" actuators.
5. Provides a continuously variable blower signal which is amplified by the solid state BSC module to control blower voltage.
6. Provides an A/C clutch on-off signal which is amplified and delivered to the pressure switch by BSC module. (Scheme 2): Ford Electronic ATC Control Panel Note location of "Cooler" and "Warmer" mode buttons.

SENSORS

Electronic ATC system contains an in-vehicle temperature sensor and an ambient temperature sensor. On Mark VII, in-vehicle temperature sensor is located behind the warning lamp module. On Continental, in-vehicle temperature sensor is located behind instrument panel above the glove box.

On both models, ambient sensor is located at top rear side of the blower motor housing. (Scheme 3) Both sensors contain thermistors (temperature sensitive resistors) which provide input signals to the control panel assembly.

ASPIRATOR

The aspirator, which is located on the evaporator case at blower motor housing outlet, is connected by a hose to the in-vehicle temperature sensor. It is designed to create a slight vacuum at its elbow when air from the blower motor flows through it. In-vehicle sensor hose is connected to this elbow, which results in air from the passenger compartment being pulled through the sensor grille and across the sensor. This allows the in-vehicle sensor to input a signal to the microprocessor based upon true in-vehicle air temperature.

BLOWER SPEED CONTROLLER

Blower speed controller is attached to the evaporator lower case. (Scheme 3) It converts low current signals from the electronic control assembly to a high current, variable ground feed to the blower motor. Blower motor speed is variable. It is controlled by the electronic control assembly software and blend-air door actuator position. A delay function provides a gradual increase or decrease in blower motor speeds under all conditions.

A power transistor circuit is also contained in the blower motor control unit. It supplies voltage to the clutch cycling pressure switch, which supplies voltage to engage the A/C compressor clutch.

CONTINUOUS POSITION ACTUATORS

The continuous position actuators operate the blend door and the floor/panel mode door. These actuators are identical and therefore completely interchangeable, independent of function or mounting location. They operate in both the clockwise and counterclockwise directions and will stop at any position within their 180 degree operating range as directed by the signals from the control head.

Ford Electronic ATC System Components. Scheme 3

SELF-TEST SYSTEM

Note. To ensure accurate self test results, this procedure must be followed first before entering SELF-TEST MODE test.

The control panel head has a self test feature that aids in locating trouble in the EATC system. To get reliable results perform the following procedure

1. Turn on ignition. Set control panel to 90° and press "OFF" mode button. Wait 40 seconds. If VFD begins to flash, there is a malfunction in the continuous position actuator wiring harness, actuator or control panel.
2. If LED begins to flash, a malfunction exists in one of 2 other position actuator wiring harnesses, actuators or control panel.
3. If no flashing occurs, set control panel to 60° and press "DEFROST" mode button. Wait 40 seconds and look for a flashing VFD or LED. If no flashing occurs, then no malfunctions in the actuator drive or feedback circuits have been detected.
4. Whether or not flashing has occurred, proceed to «SELF-TEST MODE»(/lincoln/continental/vii-1982-1987/remont/automatic-hvac-system/#ac-heater-system-automatic__self-test-mode) for further diagnostic information.

SELF-TEST MODE

1. To enter self-test mode, press "OFF" and "DEFROST" mode buttons at the same time. Within 2 seconds, press "AUTO" mode button.
2. If an 88 is displayed on control panel, no malfunctions have been detected. If a control panel detectable malfunction has occurred, the appropriate error code will be displayed. See «ERROR CODE AND/OR SYMPTOM-TO-POSSIBLE CAUSE MENU»(/lincoln/continental/vii-1982-1987/remont/automatic-hvac-system/#ac-heater-system-automatic) table.
3. The error code sequence will continue until "COOLER" button is pushed. When "COOLER" button is pushed, system will revert to the "AUTO" mode at a temperature setting one less than setting before entering the self test mode.
4. Always exit self test mode by pushing "COOLER" mode button before turning off ignition. This step will ensure proper resetting of control panel when ignition is turned on.

HISSING ATC VACUUM SYSTEM OR MODE SELECTION VALVE

1. Check in-line and control panel multiple connectors for proper installation. If hiss continues, go to step 2). If hiss stops, recheck system operation.
2. Move mode lever to determine which positions leak. If all leak, go to next test. If some but not all leak, go to step 3).
3. Pinch off suspect tubes one at a time near each respective vacuum motor. If hiss continues, go to step 4). If hiss stops, check tube connection to vacuum motor, and repair or reconnect. If hiss continues, replace vacuum motor.
4. Pinch off suspect tubes one at a time near control assembly and/or in-line connector. If hiss stops, check and repair tube. If hiss continues, replace mode selector valve.

ALL MODE SELECTOR VALVE POSITIONS LEAK

1. Move temperature control lever from 65° to 85°. If hiss stops at some settings, go to next test. If hiss continues, check Black vacuum source tube from reservoir to control assembly for cuts or disconnection and repair if necessary.
2. If no problem is found, pinch off source tube at control assembly. If hiss stops, replace selector valve.
3. If hiss continues, pinch off source tube at diverter valve. If hiss stops, replace servo assembly. If hiss continues, pinch off source tube at TBL switch.
4. If hiss stops, replace TBL switch. If hiss continues, pinch off source tube at ATC sensor.
5. If hiss stops, go to step 6). If hiss continues, recheck source tube connections, reservoir and check valve.
6. Pinch off Tan tube at ATC sensor. If hiss stops, go to step 7). If hiss continues, replace ATC sensor.
7. Pinch off Tan tube at servo motor. If hiss stops, replace servo motor. If hiss continues, repair tube.

SOME TEMPERATURE CONTROL LEVER POSITIONS LEAK

1. Pinch off Black source tube at diverter valve. If hiss stops, go to step 3). If hiss continues, pinch off Black source tube at ATC sensor.
2. If hiss stops, go to step 4). If hiss continues, recheck source tubes, connections, reservoir and check valve.
3. Pinch off Purple tube at diverter valve. If hiss stops, go to step 5). If hiss continues, replace servo assembly.
4. Pinch off Tan tube at ATC sensor. If hiss stops, go to step 6). If hiss continues, replace ATC sensor.
5. Pinch off Purple tube at control panel. If hiss stops, replace selector valve. If hiss continues, repair tube.
6. Pinch off Tan tube at servo motor. If hiss stops, replace servo motor. If hiss continues, replace tube.

Scheme 4

1. Remove air inlet duct and blower housing assembly from vehicle. (Scheme 4) Remove 4 blower plate mounting screws and remove blower motor and wheel assembly from housing. Do not remove mounting plate from motor.
2. Remove blower wheel from motor shaft. To install, reverse removal procedure, installing blower wheel 3 1/2" to 3 5/8" (89 to 92 mm) from blower mounting plate. (Scheme 4): Exploded View of Blower Motor Assembly

CLUTCH CYCLING PRESSURE SWITCH

Note. Discharging the A/C system is not necessary because switch is in a Schrader valve type of fitting.

Disconnect wiring harness from pressure switch. Unscrew pressure switch from accumulator. To install, reverse removal procedure. Tighten switch finger tight only.

Scheme 5

1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect and remove battery. Disconnect refrigerant lines at condenser. Both lines are connected with spring-locked couplings. (Scheme 5)
2. Attach special tool (T81P-19623-G) to release spring. Close tool around coupling and push into cage toward condenser. Pull hose away from condenser and unclamp tool from disconnected coupling.
3. Remove 4 bolts attaching condenser to radiator support. Remove condenser. To install, reverse removal procedure. Use new "O" rings lubricated with clean refrigerant oil. Charge A/C system. NOTE: Do not use standard "O" rings in spring lock couplings. Use only E35Y-19D690-A "O" rings. (Scheme 5): Spring Lock Coupling and Tool

1. Disconnect battery ground. On Continental, remove ashtray receptacle and 4 screws attaching center finish panel to instrument panel at ash tray opening. On Mark VII, remove right hand finish panel attaching screws.
2. On both models, pull lower edge of finish panel away from instrument panel. Disengage upper tabs of finish panel from instrument panel. Remove finish panel.
3. Remove 4 screws attaching control panel to instrument panel. Slide control panel out from instrument panel opening.
4. Disconnect 2 wiring harness connectors from back of control panel. To install, reverse removal procedure.

EVAPORATOR CORE

Note. Steps 1 through 6 are for instrument panel removal on Continental only. Instrument panel removal for Mark VII not available.

Scheme 6

1. Remove panel below glove box. Remove ash tray. Remove instrument panel to floor attaching screws. Remove cowl side trim panels.
2. Remove cowl side instrument panel attaching screws. Remove the trim panel from below steering column. Remove steering column opening cover.
3. Remove steering column shroud. Disconnect PRNDL indicator from steering column. Remove hood release handle. Remove left and right instrument panel moldings.
4. Remove switch knobs. Remove instrument panel lens assembly. Remove screws attaching instrument cluster to instrument panel. Remove instrument cluster.
5. Disconnect speedometer cable. Remove safety cover. Disconnect multi-plug behind kick pad. Remove steering column nuts and lower steering column to front seat.
6. Remove screws attaching instrument panel to brake pedal support. Remove top instrument panel attaching screws. Remove instrument panel.
7. Discharge A/C refrigerant system using approved refrigerant recovery/recycling equipment. Disconnect both refrigerant hoses from evaporator core fittings and cap hoses. Drain coolant from radiator.
8. Remove heater hoses from heater core. Cap hoses and core. Remove screw attaching air inlet duct and blower housing assembly support brace to cowl top panel. Disconnect Electronic ATC wiring harness assembly.
9. Working under hood, remove 2 nuts retaining evaporator case to dash panel. In passenger compartment, remove screw attaching evaporator case support bracket to top cowl panel.
10. Remove screw retaining the bracket below evaporator case to dash panel. Carefully pull evaporator case away from dash panel. Remove case from vehicle.
11. Remove air inlet duct and blower housing assembly from evaporator case. (Scheme 6) Remove 7 screws and 6 clips retaining 2 halves of evaporator case together.
12. Separate halves of evaporator case. Remove evaporator core. To install, reverse removal procedure. Evacuate, leak test and recharge system. (Scheme 6): Exploded View of Evaporator Core Assembly

FIXED ORIFICE TUBE

Note. On FIXED ORIFICE TUBE replacement, the high pressure refrigerant line must be replaced. It is an integral part of refrigerant line.

1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Remove condenser end of refrigerant line which is connected with spring-locked couplings. (Scheme 5)
2. Attach special tool (T81P-19623-G) to release spring. Close tool around coupling and push into cage toward condenser.
3. Pull hose away from condenser and unclamp tool from disconnected coupling. Disconnect other end of refrigerant line from evaporator tube end fitting.
4. To install new refrigerant line, use new "O" rings lubricated with refrigerant oil. (Scheme 5) NOTE: Do not use standard "O" rings in spring lock couplings. Use only E35Y-19D690-A "O" rings.
5. Install new garter spring if damaged or missing. Clean refrigerant line fittings. Connect end of refrigerant line to evaporator tube end fitting.
6. Lubricate condenser end fittings with refrigerant oil. Push refrigerant line fitting into condenser line with a slight twisting motion.
7. Make sure garter spring is over flared end of refrigerant line to ensure coupling engagement. Charge A/C system.

HEATER CORE

Note. These procedures are for vehicles with air conditioning systems only. For replacement on vehicles equipped with heater systems only, see the appropriate HEATER SYSTEM article in this section.

1. Remove instrument panel and evaporator case assembly. Remove 5 screws attaching heater core cover to top of evaporator case. (Scheme 6) Remove heater core cover.
2. Lift heater core and seals from evaporator case. Remove 2 seals from heater core tubes. To install, reverse removal procedure.

LED flashes.

Electronic ATC Wiring Diagram. Scheme 7

See also:
• SELF-TEST MODE
• ERROR CODE AND/OR SYMPTOM-TO-POSSIBLE CAUSE MENU