Page 30 of 659
HEATER AND AIR CONDITIONING 1A-7
Fig.
10—Control Assembly (Chevrolet)
6. Remove the seven stud nuts attaching the blower
and air inlet assembly to the dash panel.
7.
Remove the blower and air inlet assembly from
beneath the fender.
8. The blower assembly may be removed and dis-
assembled as described under "Blower Assembly"
above.
Installation
1.
With the blower and air inlet assembly in place,
install the seven attaching stud nuts.
2.
Replace the blower motor electrical connectors.
Fig.
9—Defroster Duct (Chevrolet, Chevell^, Camaro)
4.
Disconnect the blower motor electrical connectors.
5.
Remove the water hoses from the heater core inlet
and outlet connections.
\
N
^
1
Fig.
11-Controi Assembly (Chevelle)
CHEVROLET CHASSIS SERVICE MANUAL
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HEATER AND AIR CONDITIONING 1A-8
Fig.
12—Control Assembly (Camaro)
3.
Replace the battery and radiator supply tank.
4.
Replace each heater hose to its proper core
connection.
5. Refill the radiator.
Defroster Duct
Figure 19 illustrates the installation of the Corvette
defroster duct.
Fig.
13—Chevy II Heater Components Removal
Fig.
U-Defroster Duct (Chevy 11)
CHEVROLET CHASSIS SERVICE MANUAL
Page 32 of 659
HEATER AND AIR CONDITIONING 1A-9
Fig.
15-Heater Control Assembly and Cables (Chevy II)
Resistor Removal
Two screws attach the resistor to the rear side of
the heater assembly.
Heater Assembly
Removal
1.
Drain the radiator.
2.
Remove the radiator supply tank from its support
Fig.
16—Heater Hose Routing (Chevy II)
straps and move it out of the way.
3.
Remove the battery.
4.
Remove the water supply hoses from the core
connections.
5. Remove the blower and air inlet assembly as de-
scribed above.
6. Remove the glove compartment and the panel on
either side of the instrument panel console as out-
lined in the Body Section of this manual.
Fig.
17—Corvette Heater and Blower Inlet Assembly
CHEVROLET CHASSIS SERVICE MANUAL
Page 33 of 659

HEATER AND AIR CONDITIONING 1A-10
PLATE RETAINERS
CORE BRACKET SCREWS
Fig.
18—Corvette Heater Core Removal
7. Place a protective covering (waterproof if possible)
over the carpeting under the heater.
8. Remove the two bowden cables from the instrument
panel and disconnect the wiring connectors from the
blower switch and from the resistor.
9. Carefully work the heater assembly out from beneath
the dash.
Core Removal
1.
Remove the heater assembly as described above.
2.
Remove the sheet metal nuts which retain the core
mounting plate to the core housing.
3.
Remove the screws attaching the core brackets to
the core mounting plate and separate the core and
plate. .
Installation
1.
Assemble the core to plate with non-hardening
sealer. Attach the core mounting screws.
2.
Attach the core and plate assembly to the case with
the two sheet metal nuts. The assembly is ready for
installation as described below.
Heater Assembly Installation
1.
Carefully position the heater assembly in place on
inner surface of dash panel, then install the blower
and air inlet assembly on heater studs extending
through to the engine side of the panel. Attach the
seven stud nuts.
2.
Install electrical connectors to the blower switch and
resistor and reinstall the bowden cables to the
instrument panel.
3.
Replace the blower electrical connectors.
4.
Replace the heater hoses. (See Figure 20)
5. Replace the battery and the radiator supply tank.
6. Refill the radiator and check for leakage.
7. Check heater operation and make control adjustments
as necessary.
8. Replace the console panels and the glove
compartment.
CHEVROLET CHASSIS SERVICE MANUAL
Page 34 of 659
HEATER AND AIR CONDITIONING 1A-11
Fig.
19—Heater and Defroster Cables (Corvette)
CHEVROLET CHASSIS SERVICE MANUAL
Page 35 of 659
HEATER AND AIR CONDITIONING 1A-12
I. 20—Heater Hoses-Corvette
CHEVROLET CHASSIS SERVICE MANUAL
Page 36 of 659

HEATER
AND AIR
CONDITIONING
1A-13
AIR CONDITIONING
INDEX
Page
General Description
1A-13
Four-Season System
1A-13
Controls
1A-16
Comfortron System
. 1A-18
System Components
lA-19
Controls
1A-20
Universal System
. .
1A-21
Chevy
n
All-Weather System
•
1A-21
Corvette Four-Season System
. 1A-22
General Information
. . . 1A-26
Precautions
in
Handling R-12
1A-26
Precautions
in
Handling Refrigerant Lines
1A-28
Maintaining Chemical Stability
in the
Refrigeration System
1A-28
Gauge
Set 1A-29
Charging Station
IA-29
Leak Testing
the
System
1A-29
Vacuum Pump
1A-30
Availability
of
Refrigerant-12
. . 1A-30
Compressor
Oil 1A-31
Compressor Serial Number
1A-31
Inspection
and
Periodic Service
1A-31
Pre-Delivery Inspection
1A-31
6,000 Mile Inspection
1A-32
Periodic Service
, 1A-32
Installing Gauge
Set to
Check System Operation
....
1A-32
Performance Test
1A-32
Performance Data lA-r33
Comfortron System Operational Test
1A-33
Chevrolet Comfortron Tester
1A-34
Complete System Checks
1A-35
Maintenance
and
Adjustments ......
1A-37
Evaporator Comtrol Valve (POA)
.
1A-37
Page
Thermostatic Switch
1A-37
Expansion Valve
1A-41
Engine Idle Compensator
. . .
1A-42
Evacuating
and
Charging Procedures
1A-42
Purging
the
System
1A-42
Evacuating
and
Charging
the
System
1A-43
Checking
Oil . 1A-43
Component Replacement
and
Minor Repair
1A-45
Refrigerant Line Connections
1A-45
Repair
of
Refrigerant Leaks
1A-46
Preparing System
for
Replacement
of
Component Parts
. 1A-46
Foreign Material
in the
System
.
1A-47
Condenser
.
1A-48
Receiver-Dehydrator
1A-48
Evaporator
1A-49
Expansion Valve
1A-57
Evaporator Control Valve (POA)
1A-59
Thermostatic Switch
or
Blower Switch
. .
1A-59
All Weather-Pull Cable
1A-61
Blower Assembly
1A-62
Air Inlet Valve
.
1A-64
Blower
and
Evaporator Assembly
1A-64
Air Distributor Assembly
and
Outlet Ducts ...... 1A-64
Comfortron Automatic Control Components
1A-66
Collision Procedure lA-70
Four-Season Heater Components
1A-73
Comfortron Heater Components
. . . 1A-75
Compressor
1A-76
Wiring Diagrams
1A-78
Special Tools
.
1A-84
GENERAL DESCRIPTION
Four
air
conditioning systems
are
covered
in
this
section. They are:
1.
The
Four-Season System (Chevrolet, Chevelle,
Camaro and Corvette).
2.
The Comfortron System (Chevrolet).
3.
The All Weather System (Chevy n).
4.
The Universal System (Chevrolet, Chevelle, Chevy
n,
Camaro)
Underhood components (that
is, the
compressor,
con-
denser
and
receiver-dehydrator)
are
much
the
same
in
type,
location
and
method
of
attachment
on all of
the
above systems. The six-cylinder reciprocating compres-
sor
is
bracket-mounted
to the
engine
and
belt driven
from
the
crankshaft pulley.
The
condenser
is
mounted
ahead
of the
engine cooling radiator
and the
receiver-
dehydrator
is
mounted
in
the refrigerant line downstream
of
the
condenser.
All
cooling system components
are
connected by means
of
flexible refrigerant lines.
Evaporator size
and
location differ from system
to
system
as do
methods
of
temperature control
and air
supply
and
distribution.
FOUR-SEASON SYSTEM
The Four-Season system used
in the
Chevrolet,
Chevelle, Camaro,
and
Corvette vehicles
may be
iden-
tified
by the
fact that
it
uses
an
evaporator pressure
control known
as the POA
(Pressure Operated Absolute)
suction throttling valve.
Both
the
heating
and
cooling functions
are
performed
by this system.
Air
entering
the
vehicle must pass
through
the
cooling unit (evaporator)
and
through
(or
around)
the
heating unit,
in
that order, and the system
is
thus referred to
as a
''reheat" system.
The evaporator provides maximum cooling
of the air
passing through
the
core when
the air
conditioning sys-
tem
is
calling
for
cooling.
The
control valve acts in the
system only
to
control
the
evaporator pressure
so
that
minimum possible temperature
is
achieved without core
freeze-up.
The
valve
is
preset,
has no
manual con-
trol,
is
automatically altitude compensated,
and non-
repairable.
The heater core will be hot
at
all times since no water
valve
is
present
in
the system.
System operation
is as
follows (See Figure 24 and 25):
Air, either outside
air or
recirculated
air
enters
the
system
and is
forced through
the
system by the blower.
As
the air
passes through
the
evaporator core,
it
receives maximum cooling
if
the
air
conditioning controls
are calling
for
cooling. After leaving
the
evaporator,
the
air
enters
the
Heater
and Air
Conditioner Selector
Duct Assembly where,
by
means
of
manually operated
diverter doors,
it is
caused
to
pass through
or to
bypass
the heater core
in the
proportions necessary
to
provide
the desired outlet temperature. Conditioned airflow then
enters
the
vehicle through either
the
floor distributor
duct
or the
dash outlets. Remember that the heater core
CHEVROLET CHASSIS SERVICE MANUAL
Page 37 of 659
HEATER AND AIR CONDITIONING 1A-14
Fig.
21—Four-Season System Components (Chevrolet)
Fig.
22—Four-Season System Components (Chevelle)
CHEVROLET CHASSIS SERVICE MANUAL