HEATER AND AIR. CONDITIONING 1A-24
Fig. 35-Controls-AII Weather (Chevy II)
The heater components of the system are similar to
the standard Corvette heater with hoses routing engine
coolant to and from the heater core. A vacuum operated
shutoff valve assures that no coolant will pass through
the heater core until the system calls for heat.
Four control knobs surrounding the clock on the in-
strument panel center console provide full control of the
heating and cooling functions of the air conditioning
system.
The general arrangement of the system components
is pictured in Figure 37 while a schematic view of the
system will be found in Figure 36.
Controls Corvette
Four control knobs, grouped around the clock on the
instrument panel central console, provide full control
of the heating and cooling functions of the Corvette Air
Conditioning System. Each of the knobs, through a bowden
cable, operates one of the air diverter doors in the air
distributor assembly. In addition, the AIR COND.-PULL
knob operates the compressor switch; blower speeds are
controlled by turning the AIR PULL knob; and the heater
hot water valve vacuum switch is actuated by the COOL
IN-HQT PULL knob.
Air Conditioning "ON" Knob
The "AIR COND. PULL" knob controls the positioning
of the air diverter door which routes conditioned air
through either the dash diffuser ducts or the floor dis-
tributor outlets. Movement of this knob (hence, movement
of the selector door) also controls' the compressor
switch. When the door is positioned to send air through
the dash outlets the compressor is automatically turned
on to place the cooling system in operation and the fan
is turned on to LOW speed.
Blower Switch and Air Selector
The AIR PULL-FAN knob operates the selector door
in the right hand plenum chamber and may be set to allow
full outside air, full inside air, or a mixture of the two to
DEFROSTER DOOR
OPERATED BY
DEFROSTER KNOB
AIR CONDITIONING DOOR
OPERATED BY
AIR COND. PULL KNOB
BLOWER
OPERATED
BY TURNING
AIR KNOB
AIR DOOR
OPERATED
BY PULLING
AIR KNOB
OUTSIDE
AIR
CONTROLS
HEAT DOOR
OPERATED BY
COOL IN-HOT PULL
KNOB
L.H. OUTLET
CENTER
OUTLET
R.H. OUTLET
AIR COND.
PULL
COOL IN
HOT PULL
AIR PULL
LO-MED-HI
DEFROSTER
PULL
Fig.
36—Corvette Four-Season System Schematic
CHEVROLET CHASSIS SERVICE MANUAL
HEATER AND AIR CONDITIONING 1A-26
clockwise for medium and high blower speed, as
desired. Low blower speed is automatic during
cooling operations.
4.
"Def-Pull". This knob should be pushed fully in.
Additional Cooling Hints
1.
The center barrel outlet in the dash may be rotated
to deflect air as desired or used to act as a shut off
door.
2.
The right and left ball outlets may be rotated to
deflect air in the direction desired. Each outlet has
a shut off valve operated by a knob approximately
4 in. inboard. When the knob is horizontal, the valve
is open.
3.
There are two (2) additional outlets in the bottom of
the ducts approximately 6" inboard from the valve
knobs. A rotating cover will open these outlets to
provide cool air for the feet if desired.
4.
When first entering a very warm car, open the
windows for a few minutes until the interior of the
car has cooled off.
Heating
1.
"Air Pull-Fan". Pull this knob fully out. Rotate
the knob clockwise for low, medium or high blower
speed as desired. If just a small amount of heat is
desired, leave the fan on low or medium speed and
regulate the temperature with the "Cool In-Hot Pull"
knob.
2.
"Air Cond-Pull". This knob should normally be
pushed fully in. However, during cool, damp days
it is possible, by pulling this knob fully out, to de-
humidify the air by passing it through the evaporator
core before reheating to the desired outlet
temperature.
3.
"Cool In-Hot Pull". Pull this knob out as far as
necessary to provide the temperature desired.
4.
"Def-Pull". Pull this knob all the way out for
maximum defrosting or de-icing. When the knob is
partly out, a portion of the hot air is used for de-
frosting and the balance is discharged through the
heater outlet.
GENERAL INFORMATION
In any vocation or trade, there are established proce-
dures and practices that have been developed after many
years of experience. In addition, occupational hazards
may be present that require the observation of certain
precautions or use of special tools and equipment. Ob-
serving the procedures, practices and precautions of
servicing refrigeration equipment will greatly reduce the
possibilities of damage to the customers' equipment as
well as virtually eliminate the element of hazard to the
serviceman.
PRECAUTIONS IN HANDLING REFRIGERANT-12
Refrigerant-12 is transparent and colorless in both the
gaseous and liquid state. It has a boiling point of 21.7^
below zero and, therefore, at all normal temperatures
and pressures it will be a vapor. The vapor is heavier
than air and is noninflammable, nonexplosive, non-
poisonous (except when in contact with an open flame)
and noncorrosive (except when in contact with water).
The following precautions in handling R-12 should be
observed at all times.
• All refrigerant drums are shipped with a heavy metal
screw cap. The purpose of the cap is to protect the
valve and safety plug from damage. It is good .prac-
tice to replace the cap after each use of the drum.
• If it is ever necessary to transport or carry a drum
or can of refrigerant in a car, keep it in the luggage
compartment. Refrigerant should not be exposed to
the radiant heat from the sun for the resulting in-
crease in pressure may cause the safety plug to
release or the drum or can to burst..
• Drums or disposable cans should never be subjected
to high temperature when adding refrigerant to the
system. In most instances, heating the drum or can
is required to raise the pressure in the container
higher than the pressure in the system during the
operation. It would be unwise to place the drum on a
gas stove, radiator or use a blow torch while pre-
paring for the charging operation, for a serious ac-
cident can result. Don't depend on the safety
plug - many drums have burst when the safety plug
failed.' Remember, high pressure means that great
forces are being exerted against the walls of the
container. A bucket of warm water, not over 125°F,
or warm wet rags around the container is all the heat
that is required.
• Do not weld or steam clean on or near the system.
Welding or steam cleaning can result in a dangerous
pressure buildup in the system.
• When filling a small drum from a large one, never
fill the drum completely. Space should always be
allowed above the liquid for expansion. If the drum
were completely full and the temperature was in-
creased, hydraulic pressure with its tremendous
force would result.
• Discharging large quantities of R-12 into a room can
usually be done safely as the vapor would produce
no ill effects, however, in the event of an accidental
rapid discharge of the system it is recommended
that inhalation of large quantities of R-12 be avoided.
This caution is especially important if the area con-
tains a flame producing device such as a gas heater.
While R-12 normally is nonpoisonous, heavy con-
centrations.. of it in contact with a live flame will
produce a toxic gas. The same gas will also attack
all bright metal surfaces.
• Protection of the eyes is of vital importance! When
working around a refrigerating system, an accident
may cause liquid refrigerant to hit the face. If the
eyes are protected with goggles or glasses, no
serious damage can result. Just remember, any
R-12 liquid that you can touch or that touches you is
at least 21.7"F. below zero. The eyeballs can't take
much of this temperature. If R-12 liquid should
strike the eyeballs, here is what to do:
1.
Keep calm.
2.
Do not rub the eyes! Splash the affected area with
quantities of cold water to gradually get the tem-
perature above the freezing point. The use of min-
eral, cod liver or an antiseptic oil is important in
CHEVROLET CHASSIS SERVICE MANUAL
HEATER AND AIR CONDITIONING 1A-36
(These tests should be performed with the engine at operating temperature.)
SYSTEM CHECKS
Control
Head
Setting
High
Front
Lo
Front
Lo
Front
Hi
Front
Hi
Front
Tester Settings
Function
Manual
Manual
Manual
Manual
De-ice
65° on
Temp.
Dial
Hi
Front
Hi
Front
Hi
Front
Auto-
Matic
1 1
Auto-
matic
Manual
Manual
Manual
Control
Max.
Heat
Rotate
from
Max.
Heat to
Max.
Cold
150
Max.
Cold
Max.
Cold
Max.
Cold
Max.
Heat
Max.
Heat
Max.
Cold
Voltage
Trans-
ducer
Trans-
ducer
Ampli-
fier
Trans-
ducer
Probe
Probe
Trans-
ducer
Trans.
Tester Should
Indicate:
High Blower
Maximum Heat
Reduced Blower
Speed
Complete series of
blower changes from
Hi to Lo to Hi
again.
AMPLIFIE:
Remove conn, from c
Voltage reading she
Short this lead to grc
Voltage reading she
No voltage change in<
COMPRESSOR C
Cooling System
Operation
DE-ICE i
Assuming rest of
system is operating
normally: Max. Heat
1
to windshield.
SENSOR STR
•—
TRAtfSDtfC
0-3"
Vac. Reading
8 Volts Min.
9"
Min.
Vac.
Reading
0-4 Voltage Reading
If not, check
the following:
Fuse in Slock
In Line Fuse
High Blower
Delay Relay
Duct Delay
Thermistor
High Blower
Delay Sensor
Power Servo
Blower Switch
Resistor
Blower Motor
Wiring Harness
Blower Switch
Master Delay
Thermistor
Master Delay
Relay
Resistor
Power Servo
Blower Motor
CHECK
Resistor
I CHECK
Electrical Diagram
Probe Points:
1-2
8-9
10-21
20
18
19
*
9-46
-r
^2-3
15
16
Checked during
above procedure.
(This is a com-
plete step-by-step
high blower circuit
check which also
checks wiring
harness.)
4
5
6
L2-13
L4
""§2-15
39-46
1
16 1
14
22-40-42-44-15
.ontrol head temperature dial.
>uld be 9 volts minimum,
jund.
>uld be 0 volts,
iicates malfunctioning of amplifier.
JUTCJH CHUCK
Compressor Clutch
(Grille Temp, must
be above 40°.)
IRCUIT
Blower Switch
Master Delay
Relay
Transd
NGCl
ucer
Sensor String
2R CHECK
Transducer voltage
&t Max. Cold
position)
Transducer Ground
Hi Blower Outside
air (air door closed
to car body). Hot air
from heater outlets.
Hi Blower Recirc.
Air (air door open
to car body) cold air
from A/C outlets.
24-25-26-27-28
Voltmete
should re
ad
Battery Voltage
Battery Voltage
Battery Voltage
. Vtinimum
6
volts
Battery Voltage
Minimum
6
volts
Battery Vo]
Batterv Vo]
Ltage
Ltage
Battery Voltage
Batterv Voltage
3a
Bai
:terv Vo
tterv Vo
tage
tage
Minimum
6
volts
Batterv Voltage
Minimum
6
volts
Battery Voltage
Minimum
8
volts
Minimum 8 volts
Minimum 8 volts
Batterv Voltage
Minimum 8 volts
1 III • II »ll. —..• —•— . !!•• 1
Battery Voltage
3-23
20-10-21
38
29-30-31-32-33-
34-35-36
37-38
Defective Power Servo; Leak in Vacuum
System; Temp.; Door Link Disconnected
or Jammed; Defective Vacuum Relay
Valve
Defective Mode Door Diaphragm
Batterv Voltage
Battery Voltage
Zero Voltage
Battery Voltage
Battery Voltage
CHEVROLET CHASSIS SERVICE MANUAL
HEATER AND AIR CONDITIONING 1A-54
Fig.
71-Wiring-AH Weather (Chevy II)
1.
Loosen the lock screws and remove the two control
knobs from the front of the evaporator unit. Then
use a suitable spanner wrench to remove the two
nuts beneath the control knobs.
2.
Remove the screws (located in the outer ball outlets)
attaching the face plate.to the evaporator case. Then
remove the face plate and, reaching through this
opening, carefully remove the plug attaching the
thermostatic switch capillary tube to the evaporator
core.
3.
Turning the unit over, remove the screws attaching
the back cover and gasket to the case and remove
the cover and gasket.
4.
From the top of the case, remove the screws attach-
ing the evaporator core brackets to the case.
5.
Carefully draw the core and expansion valve assem-
bly out of the case.
NOTE: The air conditioning "on" door bowden
cable, which extends through the core, will also
be removed at this time.
6. Remove the expansion valve power element from
the low pressure line.
7.
Disconnecting the high pressure and low pressure
lines from the valve, remove the valve from the
core.
8. At this point either the expansion valve, evaporator
core or both may be replaced.
a. If replacing the expansion valve, use new etO"
rings and make the connections carefully to
eliminate possible refrigerant leaks. Position
the power element bulb so that it lies flush with
the low pressure line and has the insulating
material properly in place.
b.
If the evaporator core is to be replaced, it will
be necessary to remove the air conditioning
door bowden cable from the core and install it
in the same location in the replacement core.
If no passage has been provided for this purpose
in the replacement core, a pointed instrument
such as a pencil may be forced through core
vanes at the proper location to provide the re-
quired opening. Also remove the spacer bracket,
nut and screw from the inlet and outlet pipes of
the evaporator core and place them in a like
position on the replacement core.
CHEVROLET CHASSIS SERVICE MANUAL
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-74
Fig.
108—Comfortron Power Servo Installation
4.
Disconnect heater' hoses from heater core (at
firewall).
5. Remove glove box door.
6. Remove glove box interior.
7. Disconnect right, left, and center air conditioning
outlet hoses from distributor duct.
8. Remove air distributor duct from heater
housing.
9. Disconnect hose and cable clamps from heater
housing.
10.
Remove the remaining three heater housing stud
retaining nuts (engine compartment) and one upper
retaining screw (inside vehicle).
11.
Pull the unit away from the firewall and out of the
car.
ADJUSTMENT
SCREW
Fig.
109—Mode Shift Vacuum Diaphragm
Fig. 110'—Compressor Mount—L-6 Engines (Typical)
12.
Remove heater.housing cover from heater housing.
13.
Remove heater core from heater housing cover by
removing four (4) retaining screws and two "U"
clamps.
14.
Remove heater core.
Installation
1.
Replace core in case using a non hardening sealer.
Attach the core clamps and retaining screws.
2.
Attach the heater housing cover to the housing.
3.
Position the unit against the firewall and attach
it with the retaining screw at the top of the case.
4.
Attach the sheet metal nuts to the case studs which
project through the firewall to the engine side.
5. Connect the control cables to the control doors and
case.
6. Attach the air distributor duct to the case.
7. Connect the left, right, and center outlet hoses.
8. Replace the glove box assembly.
9. Connect heater hoses to core tubes.
10.
Replace fender assembly.
11.
Fill cooling system and connect battery cable.
Camaro
Lower Heater Hose
Removal
1.
Drain radiator.
2.
Remove side mouldings and retainers.
3.
Remove lower fender attaching bolts.
4.
Remove skirt to fender and skirt to reinforcement
bolts.
5. pry the skirt away from the fender flange and away
from the firewall. Block the skirt (four inchlengtti
of 2 x 4) clear of the lower hose and proceed with
the hose replacement.
Installation
1.
Connect the hose.
2.
Remove the block, move the skirt into position and
install all attaching bolts.
3.
Replace fender attaching bolts and mouldings.
4.
Refill cooling system.
CHEVROLET CHASSIS SERVICE MANUAL
HEATER AND AIR CONDITIONING 1A-82
•BATTERY
(POS)
CABLE
NOTE
When
control
switch*
is !TOFF"
&
Air
Cond
is
"ON"
(Control
knob
pulled
but) the
blower
fan'will
run at low
speed.
CONTROL
SWITCH
CONNECTIONS
OFF
LOW
MED
HIGH
B
TO
NONE
B
TO L
BTOL&M
B
TO L
&
H
COMPRESSOR
GROUND
WIRE
ASM
BATTERY
(NEGATIVE)
CABLE
COMPRESSOR
ASM
DASHPAJSTEL
GROMMET
16DG
CONTROL
SWITCH
RESISTOR
ASM
14LBL
14BRN
CLUTCH
COIL
EXTENSION
WIRE
ASM
-14BRN--N
JUNC
BLOCKi
OSTATIC
SWITCH
CONTACTS
NORMALLY
CLOSED
STARTING
MOTOR
SOLENOID
BLOWER
MOTOR
AIR
COND
CONTROL
(PUSH-PULL)
KNOB
DOOR
SWITCH
(PUSH
BUTTON
NORMALLY
CLOSED)
RELAY
ASM
HORN
RELAY
DIVERTER
DOOR CABLE
FUSE
PANEL
EVAPORATOR
ASM
IGNITION SWITCH-
ACCESSORY TERMINAL)
Fig. 118—All Weather Wiring Diagram (Chevy II)
CHEVROLET CHASSIS SERVICE MANUAL