Heater Systems Ford Cab & Chassis Ranger

DESCRIPTION

The standard and Hi-Output heaters are blend-air design heating systems. The major difference between the 2 systems is the heater core size and heater case. The Hi-Output heater has a larger heater core than the standard heater and a modified heater case to accept the larger heater core.

The heater system consists of 3 major components: the heater case assembly, plenum and defroster nozzle. The heater is located in the engine compartment and contains the blower motor and wheel, heater core, temperature blend door and blower resistor.

The plenum is located in the passenger compartment and contains the heater-defroster door. The defroster nozzle is a 3-outlet nozzle and connects to the defroster outlet of the plenum. The Hi-Output heater is standard on all 6.9L diesel engines. It is optional on all other vehicle applications.

VENTILATION SYSTEM OPERATION

The ventilation system is operated by ram-air from the forward motion of the vehicle. Air enters through the cowl top grille and is forced through cowl ducts to the vent assemblies located in each side cowl. Sliding vent knob rearward opens vent. Air flow can be regulated by positioning knob as desired between open and closed positions.

HEATER SYSTEM OPERATION

Standard and Hi-Output heater systems receive outside air from the cowl top grille for system operation. Outside air enters the blower from the cowl air intake and is forced through and/or around the heater core, through an opening in the dash panel into the plenum. Air is directed to the floor, defroster nozzle or both the floor and defroster nozzle depending on position of function selector lever.

The system is controlled by cables connected between the control assembly, located in the lower center of the instrument panel, and the plenum and heater case. The function selector lever operates the heater-defroster door located in the plenum and the temperature lever operates the temperature blend door in the heater case. Air flow volume is controlled by a blower switch and resistor assembly to provide 3 blower operating speeds and an "OFF" position.

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 thermal limiter temperature 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.

MODE CONTROL CABLE ADJUSTMENT

Note. The mode cable is self-adjusting with movement of control lever to right end of slot "DEFROST" position. To prevent kinking of control cable wire, a pre-set adjustment should be made before attempting to perform self-adjustment operation. The pre-set adjustment may be performed either in the vehicle with the cable installed or before installation of the cable.

BEFORE INSTALLATION

1. Insert blade of a small pocket screwdriver in end loop (crank arm end) of mode control cable. (Scheme 3) Grip self-adjusting clip with pliers and slide it down control cable wire until it is approximately one inch away from end loop.
2. Install cable assembly. Move control lever to right end of slot, "DEFROST" position, to position self adjusting clip. Check system for proper control operation.

Mode Control Cable Adjustment (Bronco, "E" & "F" Series). Scheme 3

AFTER INSTALLATION

1. Move control lever to left end of control assembly slot. Hold crank arm firmly in position. Insert blade of a small pocket screwdriver into wire loop. (Scheme 3) Pull cable wire through self-adjusting clip until a space of approximately one inch exists between clip and wire end loop.
2. Move control lever to right end of control assembly slot "DEFROST" position, to position self-adjusting clip. Check system for proper control operation.

TEMPERATURE CONTROL CABLE ADJUSTMENT

Note. The temperature control cable does not normally require adjustment. Check for proper cable operation as follows.

1. Move temperature control lever all the way to left and then all the way to right. When released, lever should bounce back slightly from both extremes of travel, indicating that blend door is sealing properly. The lever will not usually bottom out at either end of control lever slot. Bottoming out is acceptable if lever bounces back as noted above.
2. If temperature control lever moves all the way to "WARM" or "COOL" end of slot without bounce back, maximum or minimum heat cannot be obtained. The temperature control cable should be reworked as follows
3. Remove screw attaching cable to heater case assembly. Two drill dimples can be seen on cable mounting flange. If maximum heat cannot be obtained, drill an 11/64" diameter hole in dimple closest to heater case crank.
4. If minimum heat cannot be obtained, drill an 11/64" diameter hole in dimple furthest from heater case crank. Install cable using newly drilled hole. Check cable function.

HEATER SYSTEM TROUBLE SHOOTING

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.

Bronco & "F" Series

Place temperature control lever in "WARM" position and mode control lever in "HEAT" position. Insert probes of voltmeter into connector at rear of blower motor and make contact with wire terminals. Measure voltage drop across motor. With engine running, voltage should be as specified for each switch position. See BLOWER TEST SPECIFICATIONS table.

"E" Series

1. Fabricate a short jumper wire with male and female spade connectors. Strip insulation from female end. Separate blower motor feed wire at line hardshell connector (Orange/Black wire) near blower motor and connect jumper wire in blower motor feed wire circuit.
2. Connect positive lead of a voltmeter to jumper wire female connector. Connect negative lead of voltmeter to a good ground. Place temperature selector lever in mid-position for an average air flow around and through heater core.
3. Place function selector lever in "HEAT" position and turn ignition switch to "ON" position. Move blower switch to "HI" position. With a fully charged battery, blower voltage should be within specified range for each blower switch position as indicated in BLOWER TEST SPECIFICATIONS table.

"E" Series (Auxiliary Blower)

Insert probes of voltmeter into wire holes of auxiliary blower motor connector. With engine running, voltage readings for each switch position should be as specified. Voltage readings must be taken between motor and resistor (ground side of motor) or voltmeter will read battery voltage. See BLOWER TEST SPECIFICATIONS table.

Bronco, "F" Series

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 TEST SPECIFICATIONS table.

1. Separate blower motor feed wire at hard shell connector (Orange/Black stripe wire) near blower motor. Attach 2 leads of an ammeter to 2 disconnected ends of connector, connecting ammeter in series with blower motor.
2. Place temperature lever in a mid-range position and mode control lever in "HEAT" position. Turn ignition on. Move blower switch to "HI" blower position. Current draw (amps) should be as specified for each blower switch position. See BLOWER TEST SPECIFICATIONS table.

1. Separate blower motor ground (Black) wire from blower motor resistor. Connect positive ammeter lead to female spade connector on motor wire and negative ammeter lead to blower motor resistor.
2. With a fully charged battery, operate blower in each switch position and record current draw (amps). The current draw for each switch position should be approximately as indicated in BLOWER TEST SPECIFICATIONS table.

BLOWER TEST SPECIFICATIONS

BLOWER TEST SPECIFICATIONS

Removal

1. Pull off radio control knobs from control shafts. Remove 2 screws attaching top of instrument panel center finish panel to instrument panel pad. Remove finish panel. Remove knobs from control assembly by placing a small screwdriver between knob spring and control panel.
2. Pull on screwdriver, applying pressure on spring retainer. Pull knob from control assembly. Remove ashtray and bracket. Remove 4 control assembly attaching screws. Disconnect wiring harness connectors from blower switch illumination light and auxiliary fuel tank switch (if equipped) and rear window switch.
3. Disengage mode and temperature cable end retainer from control panel. Remove spring nut attaching each control cable pigtail to control lever arms and remove control panel.

Installation

To install, reverse removal procedure.

1. Remove blower switch and control lever knobs. Remove control panel faceplate. Remove control mounting bracket from instrument panel. Disconnect electrical wiring connectors from main blower switch, illumination bulb and auxiliary blower switch (if equipped).
2. Remove temperature and function control cables from control assembly. Disconnect bullet type cable retainers from bracket using needle nose pliers to compress retaining ears. Both cable "S" bends are removed from bottom side of levers by rotating cable wire 90° to lever. Remove control assembly from mounting bracket.

To install, reverse removal procedure.

1. Using a magnetic or locking-blade Phillips screwdriver, remove 4 screws attaching corners of instrument panel pad. Ensure screws DO NOT fall into defroster vents. Remove 3 screws attaching top of cluster trim to instrument panel pad. (Scheme 4)
2. Remove 2 screws attaching top of instrument panel center finish panel to instrument panel pad. Remove 3 instrument panel pad attaching screws. Lift rear edge of instrument panel pad and pull pad towards rear to remove.

1. Position instrument panel pad to instrument panel, and install 4 screws to attach pad at defroster openings. Ensure screws don't fall into defroster vents. Install 3 screws to attach panel pad and cluster trim to instrument panel.
2. Install 2 screws to attach instrument panel pad and center finish panel to instrument panel. (Scheme 4) Tighten all screws securely.

Scheme 4

1. Remove first bench seat. Remove auxiliary heater cover attaching screws and remove cover. Drain cooling system. Disconnect heater hoses and plug openings. From under vehicle, disconnect auxiliary blower motor wires at connectors and disengage wiring harness from retaining strap.
2. Remove case assembly retaining screws and lift case assembly. Disengage wiring harness grommet from floor seal and remove case from vehicle.

To install, reverse removal procedure.

1. Remove glove box liner. Remove screw attaching floor air distribution duct to dash panel. Disengage duct from plenum and remove duct. Remove 2 nuts from right end of plenum. Remove nut retaining heater case to dash panel. Remove screw retaining left end of plenum to dash panel.
2. Remove 2 screws in engine compartment attaching heater case to dash panel. Disconnect mode control cable from plenum cable bracket and cable self-adjusting clip from floor-defrost crank arm. Pull heater case forward to disengage 3 heater studs from dash panel.
3. Lower plenum from under instrument panel. On some vehicles, it may be necessary to remove instrument panel lower right attaching screw and screws attaching 2 braces to lower center of instrument panel.

To install, reverse removal procedure and adjust cables.

1. Disconnect wire harness connector from blower motor. Remove 3 screws attaching blower motor and wheel from heater case. Remove blower motor and wheel from heater case.
2. Remove blower wheel hub clamp spring and tab lock washer from motor shaft. Pull blower wheel from motor shaft.

To install, reverse removal procedure.

1. Disconnect blower motor lead wire at wiring harness. Remove ground wire mounting screw from dash panel.
2. Remove 4 screws from blower motor mounting plate. Carefully remove blower motor assembly.

To install, reverse removal procedure.

HEATER CORE - BRONCO & "F" SERIES

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 SYSTEMS article in this section.

Remove heater case from vehicle as outlined under heater case below. Remove 11 screws, one bolt and nut attaching heater housing plate to heater case, and remove heater housing plate.

To install, reverse removal procedure.

Disconnect temperature cable from temperature blend door and mounting bracket on top of heater case. Disconnect wires from blower motor resistor and blower motor. Disconnect heater hoses from heater core and plug hoses w/suitable 5/8 inch plugs. Working under instrument panel, remove 3 nuts retaining left end of heater case and right end of plenum to dash panel. Remove 2 screws attaching right end of heater case to dash panel, and remove heater case from vehicle.

Position heater case to dash panel and install 2 attaching screws. Working in passenger compartment, install 3 nuts to retain heater case and plenum right end to dash panel. Connect heater hose to heater core. Tighten clamps to 13-18 in-lbs (1.46-2.03 N.m). Connect wires to blower motor resistor assembly. Connect wire harness connector to blower motor. Position temperature cable pigtail on temperature door crank arm w/pigtail up. Be sure flat washer is placed under pigtail. Then, install a new pushnut to retain pigtail on crank arm. Position temperature cable flag to mounting bracket and install attaching screw. Check system for proper operation.

HEATER CORE - ECONOLINE/CLUB WAGON

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 SYSTEMS article in this section.

1. Disconnect battery cables and remove battery. Disconnect blower resistor wiring harness. Disconnect blower motor lead wire (Orange/Black) at wiring harness.
2. Remove ground wire mounting screw from dash panel. Drain coolant from radiator. Disconnect heater hoses from heater core and plug openings. Remove strap retaining heater hoses to heater assembly.
3. Remove 5 mounting screws from inside vehicle. Remove heater assembly. Remove case seal from face of case and remove retainer. Slide core and seal assembly from case.

To install, reverse removal procedure.

AUXILIARY HEATER CORE - ECONOLINE/CLUB WAGON

1. Remove first bench seat (if equipped). Remove auxiliary heater cover attaching screws and remove cover assembly. Remove strap retaining heater core in auxiliary heater case.
2. Drain coolant from radiator. Disconnect heater hoses from auxiliary heater core. Plug openings. Disengage wire assembly from auxiliary heater core seal. Slide heater core and seal assembly out of case. To install, reverse removal procedure.

Heater Wiring Diagram (Bronco & "F" Series). Scheme 5

Heater Schematic ("E" Series With & W/O Auxiliary System). Scheme 6