Maverick and Comet Repair

Heating System
w/o Air Condition

DESCRIPTION AND OPERATION
The blower motor in the Maverick and Comet heater assembly is located behind the heater core instead of in front of it. The system has only two doors the temperature blend (5) door and the heat/defrost (7) door (Fig. I). Both doors are cable controlled. The cable from the (5) door connects to the temperature control (center) lever; the cable from the (7) door connects to the functional control (right) lever (Fig. 2).

AIR FLOW
Outside air enters the right duct of the heater assembly through the cowl opening. With the right air vent closed, the air is draw n through the (5) -blend door opening(s) through and/or around the heater core into the blower housing (Fig.1 ). The blower then forces the air into the plenum chamber where it discharges either through the defroster nozzle or the air distribution duct to the floor.

TEMPERATURE CONTROL
When the temperature control (center) lever (Fig. 2) is set at COOL, the (5) door (Fig. 1) shuts off air passage to the heater core and bypasses it directly to the blower housing unheated. As the temperature control lever is moved from COOL to WARM, the control cable moves the blend (5) door (Fig. 1) from minimum heat to full heat position to modulate the air flow through and/or around the heater core. The air through the core and the air through the by-pass chamber is then mixed as it enters the blower housing. At full WARM position, the by-pass to the blower is shut off, and all the air passes through the heater core to pick up maximum heat before entering the bower housing.

FUNCTIONAL CONTROL
The functional control (right) lever actuates a control cable connected to the heat-defrost (7) door in the plenum chamber (Fig. 2). In the OFF position, the door is closed blocking all air passages through the plenum (Fig. 1). In HEAT position, air is discharged through the air distribution duct to the floor area. In DEFROST position, air is discharged to the windshield through the defroster nozzle. Air flow can also be modulated in direct proportion to the control setting between HEAT and DEFROST positions. A single defroster nozzle, connected to the top of the plenum chamber, distributes air through two openings in the forward instrument panel to the windshield.

ADJUSTMENTS
TEMPERATURE CONTROL CABLE
1. Loosen the temperature control cable mounting clip near the (5) door crank arm (Fig. 2).
2. Move the temperature control lever to the full COOL position (upper end of control slot), and then back it off 1/8 inch.
3. Move the (5) door crank arm toward the mounting bracket as far as it will go (Fig. 2), and tighten the clip.

FUNCTIONAL CONTROL CABLE
1. Loosen the functional control cable mounting clip near the (7) door crank arm (Fig. 2).
2, Move the functional control lever to HEAT position.
3. Position the (7) door crank arm mid-way between the two dots on the plenum chamber (Fig. 2) and tighten the clip.

REMOVAL AND INSTALLATION
HEATER CONTROL ASSEMBLY, BLOWER SWITCH, AND CONTROL CABLES
To remove the heater control assembly, blower switch and/or control cables, it is necessary to remove the instrument cluster. Pull the knobs off the control levers (Fig. 3). Carefully remove the face plate by prying it off at the top and bottom alternately. If this is not done, the mounting pins may be broken. Then, remove the 3 screws retaining the heater control assembly to the instrument panel and move the assembly out through the cluster opening. If the blower switch or defogger switch is to be replaced, disconnect the switch lead and remove the switch. If the control cables are to be replaced, disconnect the cables at the control assembly (Fig. 3) and at the No. (5) and (7) door crank arms (Fig.2). If the control assembly is to be replaced, disconnect all switch leads and cables and remove the assembly. When installing the face plate, position all of the levers between the top of their slots and mid position. Position the plate so that the five pins line up with the elongated holes in the casting. Press evenly on the plate top, center and bottom until all five pins are fully engaged.

HEATER ASSEMBLY
Removal
1. Drain the engine coolant, and disconnect the battery.
1. Disconnect the blower motor ground wire (black) from the fender apron at the engine side of the dash panel.
3. Disconnect the heater hoses at the engine block.
4. Remove the five heater assembly-to-dash panel mounting nuts from the engine side of the dash panel (Fig. 4)
5. From inside the vehicle, disconnect the ignition switch and plate from the package tray and positron the switch out of the way.
6. Remove the package tray from under the instrument panel.
7. Remove the right cowl trim panel and remove the package tray bracket.
8. Remove the clips and push nuts at the (5) and (7) door crank arms and disconnect the control cables from the crank arms (Fig. 4).
9. Remove the snap rivet that attaches the forward side of the defroster air duct to the plenum chamber (Fig. 5). Move the air duct back into the defroster nozzle to disengage it from the tabs on the plenum chamber, now, tilt the forward edge of the duct up and forward to disengage it from the nozzle, and remove it from the left side of the heater assembly.
10. Disconnect the motor lead from the resistor assembly on the bottom of the heater. (Fig.4)
11. Remove the instrument panel support bracket mounting screw (Fig.4) and remove the heater case. At the same time, pull the two heater hoses in through the dash panel. Then, disconnect the hoses from the heater core in the case.

Installation
1. Place the heater on a bench and connect both heater hoses to the core.
2. Position the heater assembly to the passenger side of the dash panel while, at the same time, pushing the hoses through the holes in the dash. Then secure the heater to the
instrument panel by installing the support bracket mounting screw (Fig. 4)
3. From the engine side of the dash panel, install the five nuts that retain the heater to the dash. Then connect the blower ground wire (black) to the fender apron, and connect the heater hoses to the engine block.
4. From the passenger side of the dash panel, install the air duct to the defroster nozzle, engage the rear side of the duct to the tabs on the plenum chamber and fasten the forward side of the plenum chamber with a snap rivet (Fig. 5).
5. Connect the motor lead to the resistor assembly on the heater case (Fig. 4).
6. Connect the control cables to the (5) and (7) crank arms (Fig. 4) and install the push nuts and cable retaining clips.
7. Adjust the control cables as outlined in Section 3.
8. Install the right package tray bracket, then install the right cowl trim panel
9. Install the package tray under the instrument panel.
10. Install the ignition switch and plate on the package tray.
11. Fill the cooling system.
12. Connect the battery ground cable.

DEFROSTER NOZZLE
The defroster air duct has to be removed before the nozzle can be removed. The air duct is attached to the top of the plenum chamber by a snap rivet at the front and two tabs at the rear (Fig. 5). Remove the snap rivet and move the air duct back into the defroster nozzle to disengage it from the tabs on the plenum chamber. Now, tilt the forward edge of the duct up and forward to disengage it from the nozzle, and remove it from the left side of the heater assembly.

Four slotted flanges on the defroster nozzle engage four corresponding tabs integral with the instrument panel (fig. 5). Carefully disengage the slots from the mounting tabs. Lower the nozzle rearward to clear the plenum chamber and remove it.

BLOWER MOTOR AND WHEEL ASSEMBLY
L Remove the heater case assembly from the vehicle as outlined in the foregoing procedure.
2. Disconnect the blower motor lead wire (orange) from the resistor (Fig. 6).
3. Remove the four blower motor mounting plate nuts and remove the motor and wheel assembly from the heater assembly (Fig. 6).

HEATER CORE
1. Remove the Heater case assembly from the vehicle as outlined in this Section.
2. Remove the compression gasket at the cowl air inlet.
3. Remove the eleven clips from around the front and rear case flanges (View A, Fig. 7), and separate the front and rear halves
4. Lift the heater core from the front half of the case (Fig. 7)
5. When installing, assemble the two halves of the case as shown in View B, Fig. 7.