HEATER AND AIR CONDITIONING 1A-63
Under Dash
7. Remove ash tray and retainer, and glove box.
8. Remove blower case to air inlet adapter bracket
retaining screw.
9. Remove screw attaching air distributor to firewall.
10.
Remove nuts retaining evaporator case to lower lip
of dash. Withdraw evaporator drain tubes.
11.
Lower complete heater - air conditioning assembly.
12.
Remove screw retaining blower case to air distrib-
utor and separate them.
13.
Remove blower to case attaching screws. Disconnect
motor wire and remove blower assembly.
14.
Remove blower from motor shaft.
Installation
1.
Assemble blower to motor shaft.
2.
Mount motor in blower case and connect wire.
3.
Assemble blower case to air distributor and install
retaining screw.
4.
Lift the complete assembly into place and install
attaching screws and nuts.
5. Replace ash tray retainer and tray and glove box.
6. Replace nuts (engine side of dash) on heater case
studs and connect heater hoses.
7. Replace evaporator pipe clamp and grommet.
8. Replace the refrigerant hoses.
9. Evacuate and charge the refrigeration system and
refill the cooling system.
10.
Check system performance.
Universal Blower Assembly
Removal
1.
Remove the universal unit from its dash mounts.
2.
Remove the cover plate and separate the upper and
lower case halves. Remove blower motor mounting
strap screw and swing strap outward.
3.
Remove blower assembly. Loosen the blower wheel
setscrews and remove the wheels from the motor
shaft. . ' .
Fig.
88-Air Inlet Assembly (Chevrolet)
Installation
1.
Install the blower wheels on the motor so that the
lower blades curve toward the firewall side of the
unit when the motor is placed in the case. Tighten
the setscrews.
2.
Place the motor in the bracket with the electrical
connector side of the motor to the right side of the
bracket. Attach the mounting strap.
3.
Assemble the case halves and attach the cover plate.
4.
Remount the unit to the dash.
Fig.
87—Blower Assembly—Universal System
Fig.
89—Air Doors (Camaro)
CHEVROLET CHASSIS SERVICE
HEATER AND AIR CONDITIONING 1A-64
Fig.
90—Evaporator Wiring (Corvette)
AIR INLET VALVE
Four-Season System
Chevrolet
Figure 88 illustrates the vacuum valve which controls
the air inlet operation of the Four-Season System.
A vacuum tank and check valve is used to assure that
the air door will not change its position due to variations
in engine vacuum.
Camqro
Figure 89 illustrates the outside air inlet door assem-
bly, and the door in the kick pad which admits reeir-
culated air to the system.
BLOWER AND EVAPORATOR ASSEMBLY
(Corvette)
Replacement
1.
Remove the evaporator core as outlined under
"Evaporator Core Replacement".
2.
Remove the blower motor as outlined under "Blower
Motor Replacement".
3.
Remove the heater and air conditioning distributor
as outlined under "Air Distributor Duct Removal".
4.
Remove the remaining nuts attaching the blower
and evaporator assembly and the cover assembly
to the studs on the -firewall.
5. Replace the components removed by reversing the
removal, procedure.
AIR DISTRIBUTOR ASSEMBLY
AND OUTLET DUCTS
Four Season System
Chevrolet and Chevelle
Figures 92 through .95 illustrate the air distributor and
outlet ducts as used in the Chevrolet, Chevelle, Camaro,
and Corvette.
Corvette
Right Outlet Duct
Removal
1.
Remove the clamp screw at the inner end of the
outlet duct and loosen the clamp.
2.
Remove the screw and lock washer attaching the
duct outer mounting tab to the body hinge pillar
brace.
3.
Pull the duct and clamp down and away from the
distributor assembly. Disconnect the courtesy light.
4.
The duct extension assembly may now be removed
if desired as well as the deflector assembly. See
Figure 95.
AIR COND.
PULL
AIR PULL- DEFROSTER
FAN PULL HOT PULL
Fig.
91—Corvette Four-Season Controls
CHEVROLET CHASSIS SERVICE MANUAL
HEATER AND AIR CONDITIONING 1A-65
Fig.
92—Chevrolet Four-Season Ducts
Installation
Reverse
assembly.
the removal procedure to reinstall the duct
Left Outlet Duct
Removal
1.
Remove the two parking brake lever bracket to
dash brace attaching screws and move the lever and
cable so they will not interfere with the duct
removal.
2.
Remove the screw and lock washer attaching the duct
outer bracket to the hinge pillar support.
3.
Remove the screws and lock washers attaching the
duct assembly to the dash brace bracket.
4.
Carefully pull the outer end of the duct downward,
detaching the courtesy light from its bracket.
5. Loosen the screws clamping the outlet duct to dis-
tributor assembly flexible tubing at the outlet duct.
The outlet duct may now be removed from beneath
the instrument panel.
6. The duct extension assembly and the deflector as-
sembly may be removed, if desired, as seen in
Figure 95.
Installation
The duct assembly is installed by reversing the re-
moval instructions.
Center Outlet Duct
Removal
1.
Remove the right and left console trim panels.
2.
Remove the radio receiver.
3.
Remove the electric clock.
4.
Remove the knobs, nuts and bezels from the two
air conditioning controls above the clock, AIR COND.
PULL and COLD IN-HOT PULL.
5. Carefully pull the outlet duct and control cables
loose from the rear of the center console and work
it down and out from under the dash. The left hand
control cable runs through the left hand flexible
tubing and may be left in the tubing after it is dis-
engaged from the duct. The right hand control cable
must also be pulled from the duct assembly as the
duct is removed.
6. The center deflector barrel assembly may now be
removed if necessary. Snap off the hairpin clips to
remove the barrel and spacer washers.
Installation
Reverse the removal procedure for installation.
AIR DISTRIBUTOR ASSEMBLY
Removal
1.
Drain the cooling system radiator.
2.
Remove the heater hoses from the core pipes and
remove the cover attaching nuts and cover surround-
ing the core pipes.
3.
Remove the glove compartment assembly and the
glove compartment door.
NOTE:.
See "Section 1 - Body" for removal
and installation of body items.
4.
Remove the right kick pad.
5. Remove the right and left center console trim panels.
6. Remove the radio receiver assembly.
7. Remove the defroster duct.
CHEVROLET CHASSIS SERVICE MANUAL
HEATER AND AIR CONDITIONING 1A-66
Fig.
93—Chevelle Four-Season Ducts
8. Remove the radio speaker and grille.
9. Remove the right outlet duct.
10.
Disconnect the bowden cables from their brackets
and operating levers on the distributor assembly.
11.
Disconnect the flexible tubing from the center and
left side outlet ducts at the air distributor assembly.
12.
Remove the heated air distributor ducts from the
air-distributor assembly.
13.
Remove the single remaining distributor to dash
panel attaching nut (the others were removed from
beneath the hood when the core cover was removed
in Step 2) located at the right end of the air dis-
tributor assembly.
14.
Carefully pull the assembly out from under the
dash, disconnecting the compressor switch wiring
connector and the water valve control switch vacuum
lines.
Installation
Reverse the removal procedure to reinstall the air
distributor assembly.
COMFORTRON AUTOMATIC
CONTROL COMPONENTS
The Comfortron system is the same as the Chevrolet
Four Season system insofar as the basic system compo-
nents are concerned. , Most removal and installation
procedures wUl remain as stated for the Four Season
system except where the automatic control components
are encountered. Each such component will be covered
in the pages which follow.
CHEVROLET CHASSIS SERVICE MANUAL
HEATER AND AIR CONDITIONING 1A-67
Fig.
94—Camaro Four-Season Ducts
Heater and Air Distributor Assembly
Removal
rfooo
1.
Disconnect battery ground cable.
2.
Drain radiator (do not purge refrigerant system).
3.
Disconnect all connectors attached to the Comfortron
wiring harness which are on the engine side of the
firewall. Push the wiring harness grommet through
the firewall to the rear.
4.
Disconnect the four vacuum hoses coming from the
underdash through the large firewall grommet. Push
the hose grommet through the firewall to the rear.
5.
Remove the nuts from the heater and air distributor
case studs which project through the firewall from
the dash side.
6. Disconnect the heater hoses from the core tubes.
Under Dash
1.
Remove glove box assembly.
2.
Remove the dash center face plate, ash tray assem-
bly, and any radio and/or tape equipment.
3.
Remove the Comfortron control assembly mounting
screws and lower the control unit.
4.
Remove the vacuum line from the kick pad valve
diaphragm.
5.
Disconnect all harness connectors between the Com-
fortron harness and the rest of the dash wiring.
6. Remove the air distributor duct which supplies the
dash outlets.
7.
Remove the screws attaching the heater and air
distributor to the firewall.
8. Pull the assembly rearward then down to remove
from the dash. Pull the Comfortron wiring harness
and vacuum hose assembly through the firewall.
Installation
1.
Place the entire case assembly with wiring, vacuum
hoses,
and control assembly into the car on the floor.
2.
Pass the underhood wiring harness and vacuum hose
harness as far as possible through the appropriate
firewall holes.
3.
Lift the assembly up into position and pass the case
studs through the firewall mounting holes. Attach
the case to the firewall with the mounting screws.
4.
Mount the dash outlet air distributor duct to the face
of the case.
CHEVROLET CHASSIS SERVICE MANUAL
HEATER AND AIR CONDITIONING 1A-68
Fig.
95—Corvette Four-Season Ducts
5. Connect the various Comfortron harness connectors
to the dash wiring and connect the vacuum hose to
the kick pad valve diaphragm. Push the vacuum hose
harness and wiring harness through the firewall to
the proper location and install their respective
grommets.
6. Raise the control unit into place and install the
mounting screws. Check that all connections are
complete.
7. Replace any radio and/or tape equipment, the ash
tray assembly, and face plate.
8. Replace the glove box assembly.
9. Connect the heater hoses to the core tubes, and
attach the nuts to the case studs through the firewall.
10.
Reconnect the four vacuum hoses as follows: Purple
to the cylinder on the thermo-vacuum valve, yellow
tracer to the body of the thermo-vacuum valve, red
tracer to the vacuum source "Tee" connection, and
white tracer to the vacuum tank inlet.
11.
Connect the wiring harness to the underhood air
conditioning components.
12.
Refill cooling system, connect battery ground cable
and check system performance.
Vacuum Tank
The vacuum tank is mounted on the firewall as shown
in Figure 97. Notice that the two vacuum lines are
clamped to the vacuum tank ports. *
Thermal Vacuum Valve
This heat operated vacuum valve is located in the
heater core input line. Figure 98 illustrates valve instal-
lation with clamps attaching the water hoses as well as
the vacuum hoses in place.
Resistor Assembly
Figure 99 illustrates the location and installation of
the blower speed resistor assembly.
Relays
Two relays are used in the system, both mounted on the
evaporator case as shown in Figure 100. The mounting
bracket forms a common ground for the relays and as a
plug for the hole in the evaporator housing used in the
Four Season system for resistor installation.
Sensors (Thermistors)
Ambient Switch and Sensor
This combination unit, which engages the compressor
clutch at about 40°F and also senses outside air tem-
perature and sun load, is mounted to the firewall within
the engine compartment with its long neck extending
deep into the cowl vent plenum chamber. Figure 98 il-
lustrates this installation,
In-Car Sensor
This sensor is located beneath the lip of the instru-
ment panel overhand just to the right of the driver as
shown in Figure 101.
Removal
1.
Remove glove box assembly.
2.
Disconnect sensor wires connector at harness.
3.
Remove sensor mounting screws, remove sensor
and pull wires and connector through hole in dash.
Installation
1.
Insert connector and
through the dash hole.
wires of replacement sensor
CHEVROLET CHASSIS SERVICE MANUAL
HEATER AND AIR CONDITIONING 1A-69
Fig.
96—Refrigerant and Vacuum Hoses (Corvette)
2.
Mount the sensor to the dash and connect the wires
to the Comfortron harness.
3.
Replace glove box assembly.
Control Head
The control head is attached to the instrument panel
flange in the same manner as the Four Season Control
Panel (See Figure 105). Two screws hold the head in
place. The amplifier, blower switch and servo and
defrost control cables are all part of the control head.
Amplifier
After the control head is removed from the instrument
panel, the amplifier may be removed as shown in Figure
107.
Temperature Dial Adjustment
1.
Install Tester J-22368 as previously described.
2.
Set Tester Voltage switch to Control Calibrate
position.
3.
Start the engine (fast idle) and set Comfortron
Control lever to HI-FRONT.
4.
Switch Rocker switch to MANUAL.
5. Set Manual Control Knob to 150 ohms on scale.
6. Rotate the Control Head Temperature Dial until the
voltmeter on the tester reads 6.5 volts. The Tem-
perature Dial should now indicate 75°.
7. If the Temperature Dial does not indicate 75°, insert
Tool J-21530 in slot to the left of the Dial as shown
in Figure 106.
8. With tool in position, rotate the Temperature Dial
so that it indicates 75°F.
Transducer
Figure 104 illustrates the installation of the transducer
assembly. Vacuum lines are clamped to the transducer
vacuum ports.
Fig.
97—Comfortron Vacuum Tank
CHEVROLET CHASSIS SERVICE JWANUAl
HEATER AND AIR CONDITIONING 1A-70
Fig.
98—Comfortron Thermal Vacuum Valve
Power Servo .
The Power Servo is attached, to the distributor duct.
The entire installation consists of the Servo Assembly
and its link assembly to the TEMP door. The Servo is
attached to the Air Selector Duct as shown in Figure 108.
Mode Shift Vacuum Diaphragm
Replacement
1.
Remove the heater distributor from the vehicle.
2.
Reach into the distributor through the AIR door
opening to reach and remove the vacuum diaphragm
mounting screws and diaphragm to door link screw
(remove piug from case to reach this screw).
3.
Reverse this procedure to replace.
4.
Adjust mode door without vacuum applied to dia-
phragm. The door should be open one inch from
sealing against the air distributor opening (inside of
case).
(Figure 109).
HIGH BLOWER
DELAY RELAY
.MASTER
DELAY
RELAY
Fig.
100—Comfortron Relays
COLLISION PROCEDURE-AII Systems
Whenever a car equipped with air conditioning unit is
involed in a collision or wreck, it should be inspected as
soon as possible. The extent of damage to any or all of
the component parts and the length of time the system
has been exposed to the atmosphere will determine the
replacement of parts and processing that will be re-
quired. The greater the length of time of exposure to the
atmosphere, the greater will have been the chances for
air, moisture and dirt to have entered and damaged the
system. Every case may be entirely different so it is not
possible to establish a hard and fast procedure to follow
each time. Good judgment must be used to determine
what steps should be taken in each specific case.
The following procedure is presented as a guide for
Fig.
99—Comfortron Resistor Assembly
Fig.
101—Comfortron Sensor Installation
CHEVROLET CHASSIS SERVICE MANUAL