A/c-Heater System - Automatic Ford LTD Crown Victoria I

DESCRIPTION

Note. Components described in this article are those that differ from or are used in addition to standard A/C components to produce automatic temperature control. For A/C components and operations not described in this article, refer to appropriate MANUAL A/C-HEATER SYSTEM article in this section.

The Automatic Temperature Control (ATC) system utilizes a reheat method of air conditioning. With this type of system, all air flow from the blower passes through the evaporator core. Temperature is regulated by reheating cooled air to the desired setting.

Temperature of outlet air is varied by temperature blend door, which controls the proportion of cooled air that flows through and/or around the heater core. From this point it is mixed and directed into the distribution plenum.

The air is diverted to the heater ducts, defroster nozzles, or air conditioning registers. The necessary additional control refinements and components to obtain automatic temperature control have been added to the basic manual system.

SYSTEM CONTROLS OPERATION

The control panel consists of 3 main parts: mode selector, blower switch, and temperature control lever.

MODE SELECTOR LEVER

Mode lever controls a vacuum selector valve with 3 internal electrical switches, similar to that used on manual A/C systems. It directs source vacuum to various vacuum motors and connects vacuum to air recirculation door in "HEAT" or "FLOOR" positions. The single pole electrical switches control electrical power to the A/C clutch and blower switch.

BLOWER SWITCH

On Crown Victoria, Grand Marquis and Town Car, 4-position blower switch has "AUTO", "LO", "MED" and "HI" positions. When in "AUTO" position, blower speed is controlled automatically when vehicle interior temperature approaches set point temperature selected. On all models, blower will not run when mode selector lever is in "OFF" position.

TEMPERATURE CONTROL LEVER

This lever is connected by a cable to sensor assembly. Movement of control lever between 65°F (18°C) and 85°F (29°C) causes a corresponding movement of preload portion of the sensor assembly. This changes the bias of the sensor and determines the temperature the system will maintain.

AUTOMATIC TEMPERATURE CONTROL

Temperature control in ATC system is determined by a modulated vacuum signal produced by sensor assembly, which controls a servo vacuum motor. Temperature level changes are accomplished by a control cable between the control assembly and sensor assembly.

System air flow is controlled by the control panel assembly. A vacuum selector valve, controlled by mode control lever, distributes vacuum to various door vacuum motors, directing air flow through the A/C system.

SENSOR ASSEMBLY

The sensor assembly, located behind right side of the instrument panel above glove box, samples interior air. It contains a bi-metallic disc which reacts to the air temperature, resulting in a change in vacuum signal. The temperature control lever is attached by a cable to an arm in the sensor.

By adjusting the lever, a vacuum bias is created. Thus the modulated vacuum output is a result of both the temperature control lever bias and the air temperature sensed at the bi-metallic disc.

SERVO ASSEMBLY

The servo assembly is a large, calibrated vacuum motor and vacuum diverter valve. The vacuum motor provides various blend door positions for given vacuum levels. The attached vacuum diverter valve controls recirculating or outside air operation.

Crown Victoria, Grand Marquis and Town Car, contain an attached blower speed programmer switch. Blower speed programmer switch controls blower speed when blower speed lever is in "AUTO" position.

THERMAL BLOWER LOCK-OUT SWITCH

Thermal blower lock-out switch (TBL) is a combination vacuum valve and single-pole single-throw switch. It is located on the heater supply hose in the engine compartment. Thermal element of the switch is in contact with engine coolant.

When mode lever is in "HEAT" position but engine coolant is cold, blower cannot operate and outside air door is held in recirculation position. When coolant warms to approximately 120°F (49°C), electrical contacts in the switch close, allowing blower operation and allowing outside air door to move to outside position.

THERMAL LIMITER ASSEMBLY

Blower motor thermal limiter and resistor assembly is mounted on evaporator assembly. Blower motor switch selects from 3 resistance elements mounted on resistor board to provide 4 blower speeds.

Thermal limiter prevents damage due to overheating. In the event thermal limiter temperature exceeds 250°F (121°C), contacts open and prevent blower operation in all speeds except high blower speed.

Note. Limiter switch cannot be reset if opened by overheating. Ensure that replacement switch includes a thermal limiter device.

Scheme 1

1. Remove instrument panel pad. Move selector lever to 75°F (24°C) position. The control arm on temperature sensor should be aligned with the arrow on sensor body. (Scheme 1) If it is not, loosen screw attaching cable housing to sensor.
2. Align sensor control arm with arrow while maintaining 75° (24°C) position of temperature selector lever. Reattach cable housing, making sure temperature selector stays at 75°F (24°C) and sensor arm stays locked. (Scheme 1): ATC System Temperature Calibration LTD and Marquis are shown. Other models are similar.

READJUSTING CALIBRATION POINT

1. If given temperature setting does not provide proper cooling or heating (temperature above or below point selected), calibration point may have to be changed.
2. Determine difference of present and desired temperature settings and direction of change (higher or lower). Adjust temperature control lever position, aligning sensor arm with arrow on sensor body.
3. Loosen screw attaching cable housing to sensor, move temperature control lever to desired amount. Retighten attaching screw. NOTE: If a readjustment of temperature control lever of more than 2°F (1°C) is necessary, and cable adjustment is correct, replace sensor assembly.

COLD ENGINE BLOWER CIRCUIT INTERRUPTION

1. Turn ignition on but do not start engine. Move blower switch to "HI" position and mode selector lever to "FLOOR" position.
2. With coolant temperature less than 100°F (38°C), blower motor should not operate and outside air door should be closed. With coolant temperature above 120°F (49°C), blower should run and outside air door should be open.
3. If results are not as listed, remove radiator cap and insert thermometer into coolant. Start engine and idle until coolant temperature of at least 160°F (71°C) is reached. Blower should operate.
4. If blower does not operate, disconnect electrical connector from TBL switch and connect jumper wire between connector terminals in wiring harness.
5. If blower operates check TBL switch for continuity. If switch is open, replace switch. If switch is closed, check connector contacts.

ATC SYSTEM SELF-TESTING

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 for further diagnostic information.

ENTERING 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 «CODE AND/OR SYMPTOM-TO-POSSIBLE CAUSE MENU»(/ford/ltd-crown-victoria/i-1983-1991/remont/automatic-hvac-system/#ac-heater-system-automatic) table below.
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.

CODE AND/OR SYMPTOM-TO-POSSIBLE CAUSE MENU

LED flashes.

HISSING ATC VACUUM SYSTEM OR MODE SELECTOR 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.

REMOVAL & INSTALLATION

Note. For replacement of refrigeration components not covered in following procedures, see the MANUAL A/C-HEATER SYSTEM article in this section.

BLOWER MOTOR & FAN

1. Disconnect blower motor lead connector from wiring harness connector. Remove blower motor cooling tube from blower motor. Remove 4 retaining screws from blower mounting plate.
2. Turn motor and wheel assembly slightly to right so bottom edge of mounting plate follows contour of the wheel well splash panel.
3. While still in blower housing, lift motor and fan assembly up and maneuver it out of housing. To install, reverse removal procedure.

Scheme 2

1. Disconnect battery ground. Discharge A/C refrigerant system using approved refrigerant recovery/recycling equipment. Disconnect and cap refrigerant lines at accumulator and evaporator.
2. Disconnect 2-wire plug from pressure sensing switch on accumulator. Drain coolant from radiator. Disconnect heater hoses from heater core and plug core openings.
3. Turn steering wheel to left to position right front wheel so wheel well splash panel support is accessible. Remove screw and splash panel support bracket from back portion of wheel well.
4. Remove 6 screws from right side hood seal bracket assembly. Remove copper hood ground clip from underneath hood seal. Remove hood seal assembly from right side of vehicle.
5. Disconnect emission hose that passes over top of evaporator case assembly. Disconnect blower motor ground wiring. Disconnect blower motor power wiring and 2 large wiring harnesses crossing evaporator assembly and position out of way.
6. Fold back carpet on passenger's side and remove bottom left screw of 2 screws supporting inlet recirculating air assembly.
7. Disconnect ambient sensor air tube from evaporator sensor air tube port. From under hood, remove nuts from evaporator assembly mounting studs, and remove 2 screws from blower motor assembly.
8. Pull evaporator assembly off 2 bottom studs, then off top stud. Maneuver case up and over wheel well splash panel.
9. Remove screws attaching panel seal to right half of evaporator case and remove heat shield from bottom of case. Remove screws holding case halves together and separate case halves.
10. Remove accumulator and evaporator core. Disconnect accumulator line from evaporator core and remove mounting bracket screws. Separate accumulator from evaporator core.
11. To install, add 3 ozs. of clean refrigerant oil to evaporator core, use new "O" rings, and reverse removal procedure. (Scheme 2): Evaporator Case and Plenum Replacement (Crown Victoria, Grand Marquis and Town Car)

Scheme 3

1. Discharge A/C refrigerant system using approved refrigerant recovery/recycling equipment. Disconnect refrigerant line from evaporator core inlet tube connection. Cap refrigerant line to prevent dirt from entering system.
2. Pour a small amount of clean refrigerant oil into evaporator core inlet tube. Engage fixed orifice tube removal tool (Motorcraft YT-1008 or equivalent) with 2 tangs on fixed orifice tube. (Scheme 3)
3. Do not twist or rotate fixed orifice tube in evaporator core. Hold T-handle of removal tool to keep it from moving and run nut on the tool down against evaporator core tube until orifice is pulled from tube.
4. If fixed orifice tube breaks in evaporator core tube, insert end of extractor (Motorcraft YT-1009 or equivalent) into evaporator core tube and thread screw end into brass tube in center of fixed orifice tube.
5. Pull fixed orifice tube from evaporator core tube. To install fixed orifice tube, lubricate "O" rings on fixed orifice tube body with clean refrigerant oil.
6. Place fixed orifice tube in removal tool and insert fixed orifice tube into evaporator core tube until orifice is seated at stop. Remove tool from fixed orifice tube.
7. Using a new, lubricated "O" ring, connect refrigerant line to evaporator core tube. Leak test, evacuate and charge system. Check for proper operation. (Scheme 3): Fixed Orifice Tube Removal

HEATER CORE

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

1. Disconnect ground cable from battery. Drain coolant from radiator. Disconnect heater hoses from heater core. Cap heater hoses.
2. Remove bolt, located below windshield wiper motor attaching left end of plenum to dash panel. Remove nut retaining upper left corner of evaporator case to dash panel.
3. Disconnect control system vacuum supply hose from vacuum source and push grommet and vacuum supply into passenger compartment. Remove glove box.
4. Loosen right door sill plate and remove right side cowl trim panel. Remove bolt attaching lower right end of instrument panel to side cowl.
5. Remove 2 screws attaching instrument panel pad to instrument panel at each defroster opening. Remove screw attaching each outboard end of pad to instrument panel.
6. On Crown Victoria models, remove pad attaching screw near upper right corner of glove box. Remove 5 screws attaching lower edge of pad to instrument panel. Remove pad.
7. Disengage temperature control cable housing from ATC sensor. Disconnect vacuum connector from ATC sensor. Disconnect electrical plug from ATC servo plug.
8. Disconnect ATC sensor tube from sensor and evaporator case connector. Disconnect vacuum harness at multiple vacuum connector near floor air distribution duct.
9. Disconnect White vacuum hose from outside-recirculation door vacuum motor. Remove 2 screws attaching passenger side of floor air distribution duct to plenum. It may be necessary to remove 2 screws attaching lower panel door vacuum motor to mounting bracket to gain access to right screw.
10. Remove the plastic push fastener retaining floor air distribution duct to the left end of plenum. Remove the floor air distribution duct.
11. Remove 2 nuts from 2 studs along lower edge of plenum. Remove plenum assembly. Remove 4 retaining screws from heater core cover. Remove cover.
12. Remove retaining screw from heater core inlet and outlet tube bracket. Remove heater core and seal assembly from plenum assembly. To install, reverse removal procedure.

Scheme 4

1. Disconnect battery ground. Remove instrument panel pad. Remove 2 mounting screws from sensor assembly. (Scheme 4)
2. Remove screw attaching control cable housing to sensor. Disconnect cable end loop from lever arm.
3. Remove cable from sensor assembly and secure cable with tape to prevent it from falling behind instrument panel.
4. Disconnect vacuum hose plug from sensor assembly. Remove ambient air hose or hoses from ends of sensor assembly.
5. To install, reverse removal procedure. (Scheme 4): Removal of Typical ATC Sensor Assembly

Scheme 5

1. Detach negative battery cable. Disconnect glove box door stop and let door hang by hinges.
2. Remove vacuum hose from servo motor and take out 2 screws from mounting bracket. (Scheme 5) Position servo to gain access to vacuum diverter valve.
3. Remove retaining push nut. Unplug multiple vacuum connector from diverter valve. Remove servo motor protective arm cover.
4. Remove push nut retaining servo motor over-travel spring and arm link to blend door crank arm. Remove servo assembly from vehicle. To install, reverse removal procedure, using a new push nut. (Scheme 5): Removal of Typical Servo Motor Assembly

CONTROL PANEL

1. Disconnect battery ground. Remove radio knobs from control shafts. Open ashtray and remove 2 screws attaching lower finish panels to ash tray opening.
2. Pull lower edge of the center finish panel away from the instrument panel. Disengage upper tabs of finish panel from instrument panel.
3. Remove 4 control assembly mounting screws. Pull control panel from opening. Disconnect electrical connections, vacuum harness and temperature control cable from control panel.
4. To install, reverse removal procedure and push on vacuum harness retaining nut. Use a new push nut on control cable attachment.

1983 ATC Vacuum Diagram (Crown Victoria & Grand Marquis). Scheme 6

1983 ATC Vacuum Diagram (Town Car). Scheme 7

1984-87 ATC Vacuum Diagram (Grand Marquis & Town Car). Scheme 8

1983 ATC Wiring Diagram (Grand Marquis & Town Car). Scheme 9

1984 ATC Wiring Diagram (Grand Marquis & Town Car). Scheme 10

1985 ATC Wiring Diagram (Grand Marquis & Town Car). Scheme 11

1986 ATC Wiring Diagram (Crown Victoria & Grand Marquis). Scheme 12

1986 ATC Wiring Diagram (Grand Marquis & Town Car). Scheme 13

1987 ATC Wiring Diagram (Crown Victoria & Grand Marquis). Scheme 14

1987 ATC Wiring Diagram (Town Car). Scheme 15

See also:
• CODE AND/OR SYMPTOM-TO-POSSIBLE CAUSE MENU