Heater System Ford LTD Crown Victoria I

DESCRIPTION

Note. All Models Except Sable, Taurus

All Ford Motor Co. heater systems are blend air systems. Outside air is drawn into blower housing and is then directed through or around heater core. Hot and cold air is mixed and then discharged through defroster outlets, vent registers or floor ducts.

Discharge air temperature is determined by a temperature blend door, controlled by a lever on control panel. Position of air door determines what portion of incoming air is passed through heater core to be heated.

Delivery of discharge air is directed by various doors. Doors may be operated either by a cable or a vacuum motor. In all cases, cables and motors are controlled by either a mode control lever or a temperature control lever on the control panel.

CONTROL LEVERS

The heater and power ventilation control utilizes a mode control lever for various modes that determine the manner in which the system will operate. A temperature control lever is used for manually setting the desired temperature and a blower switch controls the volume of air movement.

Each position of the mode control lever and blower switch is detented for positive engagement. The blower switch provides manually selected blower speeds and may be operated in any position to select the desired amount of air flow.

BLOWER MOTOR

When the blower switch is in the "OFF" position, the motor ground circuit is open and the blower motor does not operate. When the blower is in the operating position, current flow to the blower motor is restricted by 3 resistor coils in the resistor assembly.

When the switch is moved to the medium low position, one of the resistor coils is by-passed out of the circuit and current flow to the blower motor is restricted by 2 resistors.

When the switch is moved to the medium high position, 2 of the resistor coils are by-passed out of the circuit and current flow to the blower motor is restricted by only one resistor coil.

In the high position, the blower speed switch provides a current path around the 3 resistors and full current (power) is available for the blower motor to operate at full speed.

THERMAL LIMITER

A thermal limiter resistor assembly is similar to a standard resistor assembly except an overheating protective device has been added to prevent heat damage to the heater case assembly.

Overheating of the resistor coil(s) will occur when the system air flow is stopped or reduced as a result of the blower wheel becoming locked and/or is unable to turn freely.

The thermal limiter, used in the thermal limiter resistor assembly, serves as a temperature protecting fuse. It is located at a predetermined distance from the resistor coils and in series with the coil circuit. It will open the resistor coil circuit when the temperature of the thermal limiter reaches 250°F(121°C).

This interrupts blower operation in all speeds except high blower. Internal spring loaded contacts are held closed with a wax material which has a melting point of 250°F(121°C).

When the wax softens, the spring contacts separate, which opens the resistor circuit. The spring contacts cannot be closed again. As a result, it is necessary to replace the entire thermal limiter resistor assembly.

CONTROL CABLES

1. Control cables are self-adjusting with firm movement of control levers to the extreme right of the slots ("WARM" and "DEFROST" position) in control assembly.
2. To prevent kinking of the control cable wire, a pre-set adjustment should be made before attempting to perform the self- adjustment operation. The pre-set adjustment may be performed either in the vehicle (with cable installed) or before installation.
3. Pre-set adjustment before self-adjusting the cable by inserting small screwdriver in loop (crank arm end) of cable and sliding self-adjusting clip so that it is 1" away from loop. (Scheme 1)
4. Install cable, if removed, and move lever to "WARM" or DEF" position to position self-adjusting clip. Check for proper operation and repeat if necessary.

Scheme 1

TROUBLE SHOOTING & DIAGNOSIS

See HEATER SYSTEM TROUBLE SHOOTING article.

Side Switching Circuit Test (Crown Victoria & Grand Marquis)

1. Amperage readings for blower motor circuit will increase as blower speed is increased. Voltage readings across line 261 and line 57, on the blower ground side switching circuits, decrease instead of increasing as blower speed increases. Line 249 to line 57 will always read the same voltage as battery voltage.
2. A maximum blower speed switch position will produce a zero voltage reading across line 261 and line 57, as a result of blower switch by-passing the resistor assembly and connecting to the blower switch ground line 57. (Scheme 2)

Scheme 2

Mustang

1. Place temperature selector lever in the "WARM" position. Place mode selector lever in the "FLOOR" position to turn blower motor on.
2. Insert probes of a voltmeter into wire holes of hardshell connector. (Scheme 3) Measure voltage drop across motor.
3. With engine running (battery voltage approximately 14.2 volts), voltage reading should be within specified range for each switch position as indicated in BLOWER SWITCH TEST SPECIFICATIONS table.

Voltage and Current Draw Test Connections. Scheme 3

1. Disconnect blower motor wiring connector from blower motor resistor. Connect a jumper wire between motor connector Black wire terminal and resistor lower terminal.
2. Connect an ammeter between resistor top terminal and motor connector Orange wire terminal. Place temperature selector lever in WARM" position and mode selector lever in "HEAT" position.
3. With engine running (battery voltage approximately 14.2 volts), current draw should be within specified range for each blower switch position as indicated in BLOWER MOTOR TEST SPECIFICATIONS table.

BLOWER MOTOR TEST SPECIFICATIONS

INSTRUMENT PANEL

Note. Removal and installation procedures for Thunderbird and Cougar instrument panel are not available from manufacturer.

Removal (Tempo & Topaz)

1. Remove instrument panel upper finish panel and pad assemblies. Remove steering column opening cover and steering column shroud. Loosen steering column and carefully lower only enough for access to transmission gear shaft selector lever and cable assembly. NOTE: To prevent damage to selector lever and/or case, care must be used to make sure that column is not lowered too far.
2. Reach between steering column and instrument panel and gently lift selector lever cable off shift selector lever. Remove cable clamp from steering column tube. Lay steering column to rest on front seat.
3. Remove screw attaching instrument panel to brake pedal support at steering column opening. Disconnect temperature control cable from temperature blend door and evaporator case bracket. Disconnect vacuum hose connectors at evaporator case.
4. Disconnect blower resistor wire connector from resistor on evaporator housing and blower motor feed wire at in-line connector near blower resistor wire connector. Support instrument panel and remove 3 screws attaching top of instrument panel to cowl.
5. Remove screw attaching each end of instrument panel to cowl side panels. Remove 2 screws holding instrument panel to floor.
6. Move instrument panel rearward and disconnect speedometer cable and any wires that will not allow instrument panel to lay on front seat. Use care not to scratch instrument panel or steering column.

Installation

To install, reverse removal procedure.

HEATER CORE

Note. These procedures are for vehicles with heater systems only. For replacement on vehicles equipped with A/C-heater systems, see appropriate article in AUTOMATIC or MANUAL A/C SYSTEMS section.

Removal (Cougar & Thunderbird)

1. Remove instrument panel as described in this article. On Thunderbird/Cougar, remove right instrument panel brace located above heater case and attached to cowl. Drain engine coolant from cooling system and remove hoses from heater core. Plug hoses and core.
2. Remove screw attaching air inlet duct and blower housing assembly support bracket to cowl top panel. Disconnect vacuum supply hose (Black) from in-line vacuum check valve in engine compartment.
3. Disconnect blower motor wiring harness from resistor and motor lead. Working under hood, remove 2 nuts retaining heater assembly to dash panel. In passenger compartment, remove screw attaching heater assembly support bracket to cowl top panel.
4. Remove bracket-to-dash panel retaining screw located below heater assembly. Carefully pull heater assembly away from dash panel and remove heater assembly from vehicle. Remove 4 heater core access cover attaching screws and remove access cover from case. Lift heater core and seal from case. Remove seal from heater core tubes.

To install, reverse removal procedure.

Removal (Mustang)

1. Remove floor console. Remove instrument panel and lay it on front seat. Drain engine coolant from cooling system. Remove hoses from heater core. Plug hoses and core.
2. Remove screw attaching air inlet duct and blower housing assembly support bracket to cowl top panel. Disconnect vacuum supply hose (Black) from inline vacuum check valve in engine compartment.
3. Disconnect blower motor wire harness from resistor and motor head. Working under the hood, remove two nuts retaining heater assembly to dash panel.
4. In passenger compartment, remove screw attaching heater assembly support bracket to cowl top panel. Remove one screw retaining bracket below heater assembly to dash panel.
5. Carefully pull heater assembly away from dash panel. Remove heater assembly from vehicle. Remove 4 heater core access cover attaching screws and remove access cover from case. (Scheme 4)
6. Lift heater core and seal from case. Remove seal from heater core tubes.

Scheme 4

To install, reverse removal procedure.

Removal (Crown Victoria & Grand Marquis)

1. Disconnect battery negative cable. Disconnect hoses from heater core tubes. Plug ends of hoses to prevent coolant loss. Plug heater core tubes securely to prevent coolant leakage from heater core during plenum removal.
2. Disconnect control system vacuum supply hose from vacuum source and push grommet and vacuum supply hose into passenger compartment. Remove 3 glove box hinge screws. Disconnect check strap and remove glove box.
3. Loosen right door sill plate and remove right side cowl trim panel. Remove bolt attaching lower right end of instrument panel to side cowl. Remove instrument panel pad as outlined.
4. Remove bolt located below windshield wiper motor attaching left end of plenum to dash panel. Disengage temperature control cable housing from bracket on top of plenum. Disconnect cable from temperature blend door crank arm.
5. Disconnect vacuum jumper harness at multiple vacuum connector near floor air distribution duct. Disconnect White vacuum hose from outside air door vacuum motor.
6. Remove plastic push fastener retaining floor air distribution duct to left end of plenum and remove floor air distribution duct. Remove 2 nuts from 2 studs along lower flange of plenum.
7. Carefully move plenum rearward to allow heater core tubes and stud at top of plenum to clear holes in dash panel. Remove plenum from vehicle by rotating top of plenum forward, down and out from under instrument panel rearward as necessary while rolling plenum from behind instrument panel.
8. Remove 4 retaining screws from heater core cover and remove cover from plenum assembly. Remove retaining screw from heater core inlet and outlet tube bracket. Pull heater core and seal assembly from plenum assembly.

To install, reverse removal procedure.

Removal (Escort, Lynx, Tempo & Topaz)

1. Drain cooling system into a clean container. Loosen hose clamps at heater core tubes to prevent spilling coolant into passenger compartment.
2. Remove glove box door, line and lower reinforcement. Move temperature control lever to "WARM" position. Remove 4 screws attaching heater core cover to heater assembly and remove cover.
3. Working in engine compartment, loosen 2 nuts attaching heater case assembly to dash panel. Push heater core tubes toward passenger compartment to loosen heater core from heater case assembly. Pull heater core from heater case assembly and remove heater core through glove compartment opening.

To install, reverse removal procedure.

Removal (Escort, Lynx, Mustang, Tempo & Topaz)

1. Remove right ventilator assembly. Remove hub clamp spring from blower wheel hub and slide blower wheel off blower motor shaft.
2. Remove 3 blower motor flange attaching screws inside blower housing. (Scheme 5) Pull blower motor out of housing and disconnect wiring.

To install, reverse removal procedure.

Scheme 5

Remove air inlet duct and blower housing assembly. Remove 4 blower mounting plate screws. Remove blower motor and wheel assembly from blower housing. DO NOT remove mounting plate from motor. Remove blower wheel from motor shaft.

To install, reverse removal procedure, installing blower wheel on shaft with outside edge of wheel 3.75"(95.3 mm) from mounting plate.

1. Disconnect ground cable from battery. Disconnect blower lead assembly from main wiring harness. Remove blower motor cooling tube from motor.
2. Remove retaining screws from blower mounting plates. Turn motor and wheel assembly to the right so that bottom edge of mounting plate follows contour of wheel well splash panel. Lift blower assembly up and out of housing assembly.

To install, reverse removal procedure and check for proper operation.

1. Remove 3 screws securing top edge of instrument cluster bezel. Remove bezel to gain access to control panel.
2. Remove 4 screws attaching control assembly to instrument panel. Pull control rearward from instrument panel.
3. Disengage mode and temperature control cables from heater case assembly. Disconnect blower speed switch and control illumination harness connectors.
4. Remove control panel with control cables. Remove push nut which holds mode control cable end loop on mode control lever.
5. Depress White locking tang on end of mode control cable housing from mode lever tang and frame of control assembly. Remove push nut retaining temperature cable end loop on the temperature control lever.
6. Depress Black locking tang on end of temperature control cable housing. Disengage mode control cable and housing assembly from temperature lever tang and frame of control assembly.

To install, reverse removal procedure.

1. Disconnect battery ground cable. Remove instrument cluster opening finish panel. Remove 4 screws attaching control assembly to instrument panel.
2. Pull control panel from instrument panel opening and disconnect wiring. Disconnect vacuum harness and control cables from control assembly.

To install, reverse removal procedure. Retaining nut should be pushed on post rather than screwed on.

1. Disconnect battery ground terminal. Remove radio knobs and open ashtray. Remove screws attaching center finish panel at ashtray opening.
2. Pull lower edge of center finish panel out and release upper tabs of finish panel from instrument panel.
3. Remove 4 screws attaching control panel to instrument panel. Pull assembly from panel opening. Disconnect wire connectors, vacuum harness and control cables as necessary from control panel.

To install, reverse removal procedure. Retaining nut should be pushed on post rather than screwed on.

Scheme 6

Scheme 7

1. Move temperature control lever to "COOL" position and mode control lever to "OFF" position. Disconnect temperature cable self- adjusting clip from temperature door arm.
2. Disconnect temperature cable housing from mounting bracket on heater case assembly with control cable removal tool (T83P-18523- AH). (Scheme 7) Remove screw attaching passenger heater floor duct and remove duct.
3. Disconnect temperature cable from shaft and cable housing bracket on front of heater case assembly. Remove radio control knobs from radio shafts.
4. Remove 2 screws attaching cluster opening finish panel below radio opening. Remove screw attaching finish panel above heater control assembly opening.
5. Remove 2 screws at steering column opening. Remove 3 screws attaching top edge of cluster opening finish panel to instrument panel. Remove finish panel.
6. Remove 4 screws attaching control panel to instrument panel. Pull control panel out from instrument panel. Disconnect wiring harness connectors from control panel.
7. Move temperature control lever to "COOL" position. Disconnect temperature cable end retaining from control assembly bracket with control cable removal tool (T83P-18523-AH). (Scheme 7) Disconnect temperature cable from temperature lever.
8. Move mode control lever to "OFF" position. Using control cable removal tool (T83P-18532-AH), disconnect temperature cable end retainer from control assembly bracket. (Scheme 7) Disconnect mode cable from mode lever.

Scheme 8

Scheme 9

Scheme 10