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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
I A - 2 9
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. T h e 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
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