Heater System Ford Cab & Chassis Ranger

DESCRIPTION

The heater-ventilation system is a blend-air design and consists of the following components: heater blower assembly, plenum, air distribution ducts and register, control assembly, control cables and defroster nozzle. The heater blower assembly is located in engine compartment and contains the blower motor, wheel, and blower resistor.

The plenum is located in the passenger compartment and contains the heater-defroster door, temperature blend door, vent-heater door, air shut-off door and heater core. The defroster nozzle is a 3-outlet nozzle and connects to defroster outlet and plenum.

HEATER-VENTILATION SYSTEM OPERATION

When the outside air function control lever is moved to the "VENT-HEAT" position, the heater ventilation system receives outside air from the cowl top grille for system operation. Outside air enters the blower from the cowl air intake.

Air is forced through and/or around the heater core on the plenum. Air is then directed either to the floor, defroster nozzle, to both the floor and the defroster nozzle, to the instrument panel registers, or the registers and floor depending on the function control lever setting.

Air flow volume is controlled by a blower switch and a resistor assembly to provide 4 blower operating speeds plus an "OFF" position. Outside air flow can be shut off by moving the outside air function control lever to "OFF" position and turning blower switch to "OFF" position.

The system is controlled by manually adjusted cables connected between the control assembly, through cams to the air door in the plenum. The function lever operates heater-defroster door and vent-heater door located in plenum by means of a cable and cam. The temperature control lever operates temperature blend door in plenum.

TEMPERATURE CONTROL OPERATION

The temperature blend door, located in the heater case, directs outside air through the heater core for heating, or by-passes the heater core for cooling with unheated air. It is controlled by the temperature lever on the control assembly, located in the lower center of the instrument panel.

A cable assembly connects temperature control lever to temperature blend door. When temperature control lever is in the "COOL" position, the temperature blend door by-passes the heater core and the air remains unheated. When the temperature control lever is in the "WARM" position, the temperature blend door directs outside air through the heater core where the air is heated.

Positioning the temperature control lever in any position between "COOL" and "WARM" causes the temperature blend door to direct more or less outside air through or around the heater core.

BLOWER CONTROL OPERATION

The blower motor is controlled by a multi-position switch located on left side of control assembly. These operating speeds are obtained with a resistor assembly connected in series with the switch operating positions and ground side of the blower motor.

The resistor assembly also contains a thermal limiter which is used as a temperature protecting fuse. The thermal limiter is located a preset distance from the resistor coils.

If the temperature of the thermal limiter reaches approximately 250°F (121°C), the limiter contacts will open, interrupting the blower motor circuit for all blower speeds except high speed. The thermal limiter will not reset. The resistor assembly must be replaced if the thermal limiter opens.

With the switch in "OFF" position, the ground circuit of the blower motor is open and prevents blower operation. With the switch in "LOW" position, current flow in the motor ground circuit is through several resistors to obtain the lowest operating speed.

In each additional speed position, current flows through one less resistor, thereby increasing blower motor speed. In "HIGH" position current does not flow through any resistors and the blower motor operates at maximum speed.

CONTROL CABLES ADJUSTMENT

Note. To check function, temperature and/or outside air door cable adjustment, move control lever all the way to left and then all the way to right. If lever stops before end of slot at either end and then moves all the way to other end of slot without "bounce back" when released, cables should be considered misadjusted and heater output may be substandard.

1. Disengage glove box door by squeezing sides together and allow door to hang free. Working through glove box opening, remove cable jacket from metal attaching clip on top of plenum by depressing clip tab and pulling cable up. NOTE: Cable end should remain attached to door cams and/or crank arms.
2. To adjust temperature control cable, set temperature lever to "COOL" position and hold. With cable end attached to temperature door cam, push gently on cable jacket (Blue) to seat blend door (push until resistance is felt). Reinstall cable to clip by pushing cable jacket into clip from top until it snaps in.
3. To adjust function control cable, set function lever in "DEFROST" position detent and hold. With cable end attached to function cam, pull on cam jacket until cam travel stops. Reinstall cable to clip by pushing cable jacket into clip from top until it snaps in.
4. To adjust outside air cable, set outside air lever in "OFF" position and hold. Set outside air door crank arm (White) in down position (door closed to shut off air flow). With cable end attached to door crank, reinstall cable to clip by pushing cable jacket into clip from top until it snaps in.
5. Run system blower on High and actuate levers, checking for proper adjustment. Install glove box. With cable end attached to door arm, reinstall cable to clip. Turn blower switch to "HI" position and check for proper operation. Install glove box.

ADJUSTMENT PINS ADJUSTMENT

Note. If the function, outside air or temperature control levers will move neither left nor right and appear to be locked in place, the adjustment pins may have been inadvertently left in control cams during assembly. Use the following procedure to remove the pins.

1. To remove outside air door control lever, disengage glove box door by squeezing sides together and allow door to hang free. The Red pin will be evident and can be easily removed.
2. To remove function or temperature control levers, remove radio speaker (passenger side speaker if equipped with stereo radio) from top of instrument panel.
3. Working through speaker opening and using a mirror for visibility, remove the 2 Red assembly pins from control cams with mechanical fingers or a stiff wire with a hook on the end. Check for proper control cable operation. Reinstall radio speaker.

CONDITION AND POSSIBLE CAUSE

HISSING VACUUM SYSTEM OR MODE SELECTOR VALVE

1. Check in-line and control assembly multiple connectors for proper installation. Listen for hiss. If hiss stops, re-check system operation. If hiss continues, move mode lever to determine what mode valve positions are leaking. If all positions leak, proceed to step 2. If some but not all leak, proceed to step 3.
2. Check vacuum source tube (Black) from reservoir to control assembly for cuts or disconnection and reconnect or repair if necessary. Listen for hiss. If hiss stops, re-check system operation. If hiss continues, go to step 4.
3. Determine what color tubes are used in leaking mode selector valve positions. Pinch off suspect tubes, one at a time, near respective vacuum motor. Listen for hiss. If hiss continues, go to step 5. If hiss stops, check tube connection to vacuum motor and repair and/or reconnect if loose or split. Listen for hiss. If hiss continues replace vacuum motor. Re-check operation.
4. Pinch off source tube (Black) at control assembly. Listen for hiss. If hiss stops, replace selector valve. Re-check system operation. If hiss continues, re-check source tube, connections, reservoir and check valve. Service and repair as necessary.
5. Pinch off suspected tubes, one at a time, near control assembly and/or in-line connector. Listen for hiss. If hiss continues, replace mode selector valve. If hiss stops, check tube for cuts or damage. Service and repair as required. Re-check system operation.

BLOWER MOTOR VOLTAGE TEST

Place temperature lever in mid-range position. Place mode lever in "VENT" position. Insert probes of voltmeter into connector at rear of blower motor and make contact with wire terminals. With engine running, voltage should be as specified for each switch position. See BLOWER SPECIFICATIONS - BRONCO II & RANGER table below.

BLOWER MOTOR CURRENT DRAW TEST

1. Disconnect blower motor electrical connector. Connect an ammeter between left (positive) terminal on motor and corresponding terminal of wiring harness connector. Connect a jumper wire between right (ground) terminal on blower motor and corresponding terminal of wiring harness connector.
2. Place temperature control lever in mid-range position. Place mode lever in "VENT" position on Bronco II and Ranger models or HEAT" position on Bronco and Pickup models. With engine running, current draw (amperage) should be as specified for each blower speed. See BLOWER SPECIFICATIONS - BRONCO II & RANGER table below.

BLOWER TEST SPECIFICATIONS

BLOWER SPECIFICATIONS - BRONCO II & RANGER

REMOVAL

1. Remove knobs from radio shafts. Remove 4 screws attaching top of cluster finish panel to upper finish panel pad.
2. Remove cigar lighter. Remove center and left instrument trim panels. Pull headlight switch to on and detach left instrument trim panel enough to allow access to cluster finish panel lower attaching screws.
3. Remove 4 screws attaching bottom of cluster finish panel to instrument panel. Lift cluster finish panel away from instrument panel. Remove 4 screws attaching control panel to instrument panel.
4. Pull control panel through instrument panel opening far enough to allow removal of electrical connectors. Remove connectors.
5. Working from bottom of control panel using a screwdriver, release mode control cable (Black) snap-in flag from control bracket.
6. Pull enough cable through instrument panel opening until mode control cable can be held vertical to control panel. Remove control cable from mode control lever.
7. Working from top of control panel, using needle nose pliers, release temperature control cable (Blue) and outside air control cable (White). Rotate control panel 90° down. Disconnect temperature and outside air control cables from control levers. Remove control panel.

INSTALLATION

To install, reverse removal procedure. Ensure proper operation of control assembly.

Heater Control Panel Removal (Release control cable snap-in flags with needle-nose pliers.). Scheme 1

1. Disconnect battery ground. Remove heater blower assembly. Remove heater hoses from heater core tubes and plug openings. In engine compartment, remove 4 nuts from plenum studs at dash panel.
2. Remove 3 screws from steering column lower finish panel and remove panel. Remove 2 attaching screws and remove steering column shroud. Remove headlight and radio knobs.
3. Remove cigar lighter. Unsnap 3 finish trim panels from bottom edge of instrument panel. Remove ashtray. Remove 2 bolts from steering column center support bracket. Remove 3 bolts from base of steering column.
4. Remove 4 screws from underneath top front edge of instrument panel pad. Remove 3 screws each from defroster air outlets. Remove bolt from instrument panel lower center brace.
5. Remove screws from extreme bottom ends of instrument panel. Remove hex screw from instrument panel pad and emergency brake release lever support bracket. Remove 2 screws from hood release lever support bracket.
6. Remove nut from instrument panel pad support bracket located in steering column opening. Remove 4 attaching screws and instrument panel cluster. Remove 3 screws from above glove box.
7. Remove attaching screws and radio speaker grilles. Remove radio speakers. Remove instrument panel pad. Remove 3 screws from top of instrument panel. Disconnect speedometer cable.
8. Remove bolt from instrument panel and parking brake release lever support bracket. Disconnect hard shell connector at lower side behind instrument panel.
9. Remove radio antenna wire from clip attached to defroster nozzle. Disconnect control cables at plenum. Remove instrument panel from vehicle. Pull plenum away from dash panel. Remove from vehicle.

To install, reverse removal procedure.

Plenum & Heater Case Removal. Scheme 2

1. Disconnect battery ground. On vehicles equipped with 2.8L engine, remove vacuum reservoir and solenoid box cover in front of blower motor.
2. For vehicles equipped with 2.3L diesel engine, remove vacuum reservoir and washer in front of blower motor. For vehicle equipped with 2.3L EFI engine, remove air cleaner in front of blower motor.
3. On all vehicles disconnect wire harness connector from blower motor by pushing down on connector tabs and pulling connector off motor. Disconnect blower motor cooling tube at blower motor.
4. Remove 3 screws attaching blower motor and wheel to heater blower assembly. Holding cooling tube aside, pull blower motor and wheel from heater blower assembly and remove from vehicle. Remove blower wheel hub clamp from motor shaft. Then, pull blower wheel from motor shaft.

To install, reverse removal procedure.

HEATER CORE R & I

Note. These procedures are for vehicles with heater systems only. For replacement on vehicles equipped with manual A/C-heater systems, see the MANUAL A/C SYSTEM article in this section.

1. Drain coolant from radiator. Disconnect heater hoses from heater core and plug openings. Remove 5 screws from heater core access cover on plenum assembly.
2. Remove access cover. Pull heater core rearward and down, removing from plenum.

To install, reverse removal procedure.