Maverick and Comet Repair
Heating System
w/ Air Condition
DESCRIPTION AND OPERATION
AIR FLOW
Either outside air from the cowl intake or recirculated air from inside the car
enters the right duct of the heater-A/C assembly (Fig. 3). The blower motor and
wheel draws the air from the right duct of the heater-A/C assembly through the
evaporator core, through and/or around the heater core into the blower housing
and then forces it into the plenum chamber. From the plenum chamber, the air
discharges through the floor, register, or defroster outlets.
CONTROL OPERATION
The functional (right) control lever on the control head (Fig. 1) operates the
vacuum selector valve which receives vacuum from the vacuum supply tank and
.connects it to four vacuum motors (Fig. 2). The vacuum motors actuate the
outside-recirc (1) (2) door, the heater water valve (4) (partially) the A/C-Heat
door (6) and the A/C-defrost door (7).
The temperature (center) control lever (Fig. 1) is connected by a cable to a crank arm on the temperature blend (5) door (Fig. 2) which routes the air through and/or around the heater core. The movement of the crank arm also actuates the water valve vacuum switch plunger as shown in Fig. 2. This switch sends additional vacuum to the (4) motor to completely close the water valve.
Also mounted on the control head is a four-position blower switch 4operated by the switch (left) lever, and the A/C compressor clutch switch which is actuated by a cam on the vacuum selector valve (Fig. 1).
COOLING
In both MAX and FRESH A/C positions of the functional control lever, the cam on
the vacuum selector valve closes the clutch switch (Fig. 1) to engage the
compressor clutch. With the clutch engaged, the compressor pumps refrigerant
through the evaporator core for cooling. The selector valve also sends vacuum to
the top of the water valve motor (4a) which partially closes the valve (Figs. 2
and 3). If at the same time the temperature control lever is set at COOL, it
actuates the water valve vacuum switch to send additional vacuum to the motor
(4b) and completely close the valve. With the water valve closed, there is no
water flow through the heater core. If the temperature lever is set at WARM, the
water valve vacuum switch shuts off the additional vacuum (4b) leaving the water
valve partially open. There is now a partial flow of hot water through the
heater core which modulates the temperature of the cool air from the evaporator.
In MAX A/C position, the (1) (2) door is closed to outside air (vacuum), allowing inside air to recirculate in the system (Fig. 3). In FRESH A/C position (no vacuum), outside air is drawn into the system. In both A/C positions, the air is cooled as it passes through the evaporator core; and then, with the (6) door closed to the floor (no vacuum) and the (7) door closed to the defrosters (vacuum), the cool air discharges through the A/C registers.
HEATING
In OFF, HI-HEAT, LO-HEAT, FOG-DEFROST, and ICE-DEFROST positions of the
functional control lever, the cam on the vacuum selector valve is disengaged
from the A/C clutch switch (Fig. 1) leaving the switch open. With the switch
open, the compressor is not pumping refrigerant through the evaporator (no
cooling). Also there is no vacuum to close the water valve (4). With the water
valve wide open (Fig. 3), there is full flow of hot water through the heater
core.
In HI-HEAT position, the (1) (2) door (Fig. 3) is open to outside air (no vacuum) and, depending upon the setting of the temperature blend (5) door, the air is drawn through and/or around the heater core into the blower housing. Then, with the (6) door in mid-position (partial vacuum) and the (7) door closed to the defrosters (vacuum), the blower discharges the air through the floor outlet and the A/C registers.
In LO-HEAT position, the system operates in the same manner as in HI-HEAT except that the (6) door is closed to the A/C registers and defrosters (full vacuum) allowing all the air to discharge through the floor outlet.
When the functional control lever is set in FOG-DEFROST position, the system operates in the same manner as in HI-HEAT except that the (7) door is open to the defrosters (no -vacuum). Half the air discharges to the windshield, and half to the floor area.
In ICE-DEFROST position the (1) (2) door is open to outside air (no vacuum), the (6) door is closed to the floor outlets (no -vacuum) and the (7) door is closed to the A/C registers and open to the defrosters (no vacuum). All the air discharges through the defroster nozzles to the windshield.
VACUUM CONTROL SYSTEM OPERATION
The test chart in Fig. 3 will determine which vacuum motors should be
functioning with applied vacuum during the various control lever positions.
Check for proper operation by following the chart and testing the system as
follows:
1. Connect a vacuum gauge in the vacuum supply (black) Vine between the check
valve and the vacuum selector valve (Fig. 2).
2. Move the functional control lever to the last position listed (ICE-DEFROST)
on the test chart in Fig. 3. Set the temperature control to WARM.
3. Start the. engine and let it run until it is warm and a good vacuum reading
shows on the gauge. Turn the key quickly to the ACCESSORY position and observe
the gauge to see if vacuum is maintained or lost. The last control position
listed on the chart (Fig. 3) indicates that no vacuum should be applied to any
of the motors. Therefore, if the gauge shows a vacuum loss, there is a leak in
the vacuum supply (black) line or at the check valve. If the vacuum reading is
maintained, the system is OK up to the selector valve (Fig, 2). To isolate the
problem, move up to the next position listed on the chart (Fig. 3).
4. For the next position, move the functional control lever up to FOG-DEFROST
and leave the temperature control lever at WARM. Start the engine again, turn
the key quickly to the ACCESSORY position, and watch the gauge. This position on
the chart in Fig. 3 indicates that vacuum should be applied through the red line
only (6A) to the A/C-Heat door motor.
If the vacuum reading is maintained, there are no leaks in the red line or the top part of the motor. Move the lever up to the next position on the chart and check the (6b) yellow fine by repeating the test.
If the gauge indicates a vacuum loss, there is a leak in the red line or the top part of the motor. Make the repairs or replacements necessary to correct the vacuum leak before moving up to the next position.
5. Continue this test procedure up through all the
control positions to determine the motor or motors causing the problem. Make the
necessary repairs or replacements to correct the vacuum leak.
6. If no vacuum leaks are indicated1 throughout ill the control positions, check
the motor or door that could be causing the complaint. for example: Air
discharges from the floor outlet and from the defrosters, but no air comes out o
f the registers when the functional control lever is in HI-HEAT position.
Reference to the schematic in Fig. 3 would indicate that the A/C-defrost door
(7) is closed to the A/C registers and open to the defrosters (no vacuum). In
HI-HEAT, vacuum should be applied to the (7) motor for the purpose of opening
the door to the registers and closing it to the defrosters.
Disconnect the (blue) vacuum line at the No. (7) door vacuum motor (Fig, 2) and connect it to a vacuum gauge. Again, check the vacuum reading (lever at HI-HEAT) by starting the engine, building up a vacuum, and quickly turning the key to ACCESSORY position. A zero vacuum reading indicates that the line to the motor is plugged or kinked. If vacuum is indicated, either the door is restricted or the motor should be replaced.
ADJUSTMENTS
TEMPERATURE CONTROL CABLE
Move the temperature control (lower) lever (Fig. 1) to the full up and to the
full down positions.
If the lever does not contact either end of the slot, tighten the retaining screw on the cable mounting clip near the temperature door crank arm on the evaporator assembly.
If the lever contacts the upper end of the slot only, loosen the retaining screw and pull the cable down until the lever no longer contacts the upper end of the slot in the full up position, Tighten the retaining screw.
If the lever contacts the lower end of the slot only, loosen the retaining screw and pull the cable up until the lever no longer contacts the lower end of the slot in full down position. Tighten the retaining screw.
HEATER WATER VALVE VACUUM SWITCH
First make sure that the temperature control cable is properly adjusted as given
in the foregoing procedure. Then, move the temperature control lever to the full
COOL (UP) position. If the plunger on the water valve vacuum switch (Fig. 4) is
not fully depressed, loosen the adjusting screws and move the switch against the
(5) door crank arm until the plunger is fully depressed. Tighten the adjusting
screws.
If moving the vacuum switch as far as possible against the crank arm will not fully depress the plunger, readjust the temperature control cable.
VACUUM MOTORS
The (1) (2) motor and the {7) motor are adjustable. The (4) and (6) motors are
not adjustable.
A motor can be adjusted by means of an adjusting screw
Aid slot on the two-piece actuating shaft assembly. The door operated by the
motor must be in its NV (no vacuum applied) position (Fig. 3).
1. Loosen the adjusting screw.
2. Hold the air door in its NV position, and adjust the shaft so that the
preload indicator notch is flush with the motor body.
3. Tighten the adjusting screw.
REMOVAL AND INSTALLATION
CONTROL ASSEMBLY
To remove the control assembly, remove the instrument cluster. Pull the knobs
off the control levers, blower switch and defogger switch (Fig. 1). 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. Pry off the lens plate from
the control assembly, then remove the screws retaining the control assembly to
the instrument panel. Move the control assembly out through the cluster opening
and disconnect the vacuum harness multiple connector, the blower switch and
clutch switch wiring and the control cable. Remove the assembly.
When installing the control assembly, be sure to adjust the control cables. 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.
BLOWER SWITCH
Remove the control assembly from the instrument panel as outlined in the
foregoing procedure. Disconnect the wires, remove the retaining screws and
remove the switch from the control assembly (Fig. 1).
CLUTCH SWITCH
Remove the instrument cluster assembly (Part 33-50), from the vehicle. Working
through the cluster opening, disconnect the clutch switch connectors and remove
the 2 nuts retaining the clutch switch to the control assembly and remove the
switch (Fig. 1).
HEATER-AIR CONDITIONER ASSEMBLY
On the engine side of the dash panel perform the following steps:
1. Disconnect the battery and remove the air cleaner.
2. Drain the cooling system.
3. Connect a manifold gauge set to the compressor, and discharge the system.
4. Disconnect the evaporator core
tubes from the expansion valve, and apply tape over the core tubes to keep out
foreign material. Disconnect the heater hoses from the heater core tubes.
5. Remove the three A/C assembly-to-dash pane] mounting stud nuts (Fig. 4).
Working at the passenger side of the dash panel, continue as. follows:
6. To provide clearance for removing the assembly: remove the utility shelf from
the lower edge of the instrument panel (5 retaining bolts); remove the right
cowl trim panel and utility shelf bracket, and remove the, radio assembly.
7. Disconnect the right and left A/C register air ducts from the plenum chamber
(Fig. 4).
8. Remove the floor distribution duct from the blower housing.
9. Remove the center register from the instrument panel (2 screws) for
clearance. Then pull the plenum chamber part way through the register opening to
disengage it from the blower housing. Disconnect the (blue) hose from the (7)
door motor on the plenum chamber.
10. Disconnect the red .and yellow vacuum hoses from the (6) door motor and the
white hose from the (1) (2) door motor (Figs.. 2 and 4.
11. Disconnect the vacuum harness multiple connector from the vacuum selector
valve on the control assembly.
12. Disconnect the temperature control cable from the (5) door crank arm on the
evaporator housing, and disconnect the purple and green vacuum hoses from the
adjacent water valve vacuum switch (Figs. 2 and 4).
13. Remove the screw that retains the evaporator housing to the cowl upper
support, and remove the A/C assembly rearward and away from the dash panel in
order to clear the mounting studs.
14. Remove, any vacuum hose retaining tape, and disengage any hoses that may be
held by retaining clips.
15. Disconnect the wire connectors from the A/C thermostat (de-icing) switch on
the evaporator housing and from the resistor on the blower housing (Fig. 5).
Disconnect the blower motor ground wire from the windshield wiper motor mounting
bracket.
16. Pull the drain tube from the hole in the floor pan.
17. Lower the evaporator and blower housing assembly and remove it from the
vehicle.
18. When installing the assembly be sure to connect the vacuum hoses according
to the color codes as indicated in Fig. 2. When connecting to the water valve
vacuum switch, connect the purple hose to the nipple closest to the switch
plunger. The green hose leads, to the water valve motor,
19. After the assembly is installed, adjust the temperature control cable and,
if necessary, the water valve vacuum switch as outlined in Section 3 of this
part.
20. Evacuate and charge the refrigerant system with Refrigerant-12.
EVAPORATOR CORE
1. Remove the heater-air conditioner assembly from the vehicle as outlined in
the foregoing procedure, and place it on a bench.
2. Remove the flange clips from the housing assembly and separate the upper half
of the housing from the lower half (Fig. 5).
3. Remove the thermostatic (de-icing) switch retaining screws, and remove the
switch, sliding the capillary tube out of the hole in the evaporator housing
(upper half).
4. Remove the core retaining screws and remove the evaporator core from the
upper half of the housing.
5. Remove the rubber seal from the evaporator core tubes. Transfer the seal and
the core pads to the new unit.
6. After installing the new core, install the housing assembly in the vehicle.
Leak-test, evacuate and charge the refrigeration system.
HEATER CORE
J. Remove the heater-air conditioner assembly from the vehicle as outlined in
this section, and place it on a bench.
2. Remove the flange clips from the housing assembly, and separate the upper
half of the housing from the lower half (Fig. 5).
3. Remove the water valve vacuum switch from the lower half of the housing.
4. Remove the temperature blend (5) door shaft (screw and retaining clip), and
remove the (5) door upper frame (four screws), the door, and the door lower
frame (four screws) from the lower half of the housing (Fig. 5).
5. Lift the heater core out of the lower housing.
6. Before installing a new heater core, transfer the pads from the old to the
new core.
7. After installing the core, install the housing assembly in the vehicle.
Leak-test, evacuate, and charge the refrigeration system.
THERMOSTATIC (DE-ICING) SWITCH
Removal
1. Disconnect the battery ground cable.
2. Remove the instrument cluster.
3. Remove the ash receptacle (three screws), and disconnect light,
4. Remove the left duct assembly and remove the center register. Then remove the
right duct assembly.
5. Disconnect the vacuum hose from the heat/defrost door (7) at the plenum. Push
the plenum assembly to the left to gain access to the thermostatic (de-icing)
switch.
6. Disconnect the 2 connectors at the switch and remove the two screws retaining
the switch to the top of the evaporator (Fig. 5).
7. Working through the center grille opening and between the package tray and
the instrument panel, remove the thermostatic (icing) switch and pull the
sensing tube out of the core fins.
Installation
1. Feed the sensing tube into the core fins. Position the thermostatic (icing)
switch to the evaporator and install the 2 retaining screws. Connect the 2
connectors.
2. Correctly position the plenum and connect the right duct assembly. Connect
the heat/defrost door (7) vacuum hose to the plenum.
3. Install the center register assembly and install the left air duct.
4. Install the ash receptacle assembly.
5. Install the cluster assembly.
6. Connect the battery ground cable.
BLOWER HOUSING
The blower housing can be removed without removing the evaporator housing
assembly.
1. Remove the radio assembly.
2. Remove the utility shelf (5 retaining bolts), and disconnect the right and
left A/C register air duct assemblies from the plenum chamber.
3. Remove the floor air distribution duct from the bottom of the blower housing.
4. Remove the blower housing mounting stud nut and lock plate.
5. Rotate the blower housing to unlock the slotted tabs on the blower housing
from their lock pins on the evaporator housing (Fig. 5). There are two tabs and
pins. Disconnect the red and yellow hoses at the (6) vacuum motor on the blower
housing. Disconnect the resistor and ground wires, and remove the blower
housing.
BLOWER MOTOR AND WHEEL
1. Remove the blower housing as outlined in the foregoing procedure.
2. Cut the gaskets around the A/C outlets at the break line (Fig. 6).
3. Remove seven clips, and separate the left and right halves of the blower
housing.
4. Remove three blower motor mounting plate retaining nuts, and remove the motor
and wheel assembly from the housing.
5. When installing, make sure that the A/C-Heat door is positioned properly
before clipping the right and left housings together.
OUTSIDE/RECIRC (1) (2) AIR DOOR VACUUM MOTOR
To remove the recirculating door vacuum motor, remove the 2 nuts retaining the
right air register to the instrument panel utility shelf. Then remove the
inboard bolt from the right instrument pane] bracket and remove the register
assembly. Mark the position of the motor arm and remove the screw connecting the
arm to the motor (Fig. 2). Disconnect the vacuum hose from the motor, then
remove the 2 screws securing the motor to the bracket and remove the motor.
AC/HEAT DOOR (6) VACUUM MOTOR
To remove the motor, first disconnect the battery ground cable. Remove the radio
assembly (Part 35-01, Section 4). Disconnect the 2 vacuum hoses from the vacuum
motor, and remove the hose retaining clip. Remove the two nuts retaining the
motor to the mounting bracket on the blower housing, and remove the motor (Fig.
2).
HEAT/DEFROST DOOR (7) VACUUM MOTOR
Removal
1. Disconnect the battery ground cable.
2. Remove the radio assembly (Part 35-01, Section 4).
3. Remove the 2 screws retaining the center register assembly to the instrument
panel and remove the register.
4. Remove-the ash receptacle,
5. Disconnect the left and right duct assemblies from the plenum chamber.
'«. Remove the utility shelf by removing the 5 retaining bolts.
7. Disconnect the left and right air ducts from the outside registers.
8. Disconnect the vacuum hose from the blower housing.
9. Remove the floor distribution duct from the blower housing.
10. Remove the lower stud nut and lock plate retaining the blower motor to the
evaporator housing. Rotate the blower motor to disengage it from the evaporator.
Lower the blower motor to the floor.
11. Remove the A/C-defrost plenum chamber. Then remove the retaining clip and
open the door in the duct (Fig. 1).
12. Remove the 2 nuts retaining the vacuum motor to the plenum chamber and
remove motor.
Installation
1. Position the vacuum motor on the A/C-defrost plenum chamber and install the
two retaining nuts and clip.
2. Position the plenum chamber under the instrument panel, then position the
blower motor on the evaporator housing. Rotate the blower motor to lock it in
place on the evaporator housing. Install the blower housing mounting stud nut
and lock plate.
3. Connect the vacuum hoses to the blower motor housing and to the heat/defrost
door (7) vacuum motor.
4. Install the center register assembly.
5. Connect the left and right air ducts to the center register assembly.
6. Install the ash Receptacle.
7. Install the floor distribution duct on the blower assembly.
3. Install the package tray and connect the ducts to the registers at the ends
of the instrument panel.
9. Install the ignition on switch to package tray.
10. Install the radio assembly.
11. Connect the battery ground cable.
CONDENSER
1. Discharge the system, and remove both grille upper supports.
2. Remove the hood latch and support assembly.
3. Disconnect the evaporator-
to-condenser hose at the receiver tank.
4. Disconnect the compressor-to-condenser hose at the condenser, and remove the
clip holding the hoses together at the radiator support.
5. Remove the bolts attaching the condenser to the radiator front support, and
remove the condenser.
6. Transfer the receiver tank to the new condenser. .
7. Position the condenser to the radiator support, and install the attaching
bolts.
8. Connect the evaporator-to-receiver tank hose, and connect the
compressor-to-condenser hose.
9. Install the hood latch and support, and install both grille upper supports.
10. Install the clip holding the hoses together at the radiator support.
11. Leak test, evacuate and charge the system.
MAVERICK AND COMET HEATER-AIR CONDITIONER
SPECIFICATIONS
Blower Motor current Draw at 12.8 Volts....... 16A to 20 Amps on High Blower
Refrigerant Charge.........1-7/8 pounds
Protection Device...30 Amp Fuse in Fuse Panel
Control Illumination....2 CP No. 1895 Bulb
Magnetic Clutch Current Draw.....3.75 Amps. Max.