Chevrolet 10 Series 1967, Service Manual

Page: 38 / 605

HEATER AND AIR CONDITIONING 1A-10
AIR CONDITIONING
INDEX
Page
General Description..........................................................1A-10
General Information..........................................................1A-12
Precautions in Handling Refrigerant— 1 2 .................. 1A-13
Precautions in Handling Refrigerant L i n e s ............... 1A-13
Maintaining Chemical Stability in the
Refrigeration System ............................................. 1A-14
Gauge S e t ......................................................................1A-14
Charging S ta tio n ..........................................................1A-15
Leak T e s t in g ................................................................1A-15
Vacuum P u m p .............................................................1A-16
Availability of Refrigerant— 1 2 ................................. 1A-17
Inspection and Periodic Service....................................... 1A-17
Pre-D elivery Inspection............................................. 1A-17
6000 Mile Inspection................................................... 1A-17
Periodic S e r v ic e ..........................................................1A-17
Installing Gauge Set to Check System Operation . . . 1A-17
Performance T e s t ...................................................... 1A-17
Performance D a t a ...................................................... 1A-18
Evaporator Control Valve (POA)
.............................. 1A-18
Expansion V a l v e ..........................................................1A-18
Engine Idle Compensator .......................................... 1A-19
Evacuating and Charging P ro c e d u re s .............................. 1A-19
Purging the S y s t e m ....................................................1A-19
Evacuating and Charging the S y s t e m ........................ 1A-19
Checking O i l ............................................................... 1A-20
Adding Oil to the System ............................................. 1A-22
Page
Component Replacement and Minor R ep airs..................... 1A-22
Refrigerant Line Connections .................................... 1A-22
Repair of Refrigerant L e a k s ....................................... 1A-22
Refrigerant Hose F a ilu r e ............................................. 1A-23
Conditioning System for Replacement of
Component P a r t s ...................................................... 1A-23
Sight Glass R ep lacem en t............................................. 1A-23
Control A sse m b ly ................................................... . . 1A-23
Condenser......................................................... ... 1A-24
Receiver D e h y d ra to r................................................... 1A-25
Expansion Valve ......................................................... 1A-26
P.O.A. V a l v e ............................................................... 1A-26
Blower A s s e m b ly ......................................................... 1A-26
E v a p o r a t o r .................................................................. 1A-27
Blower and Evaporator C a s e ....................................... 1A-27
Heater C a s e .................................................................. 1A-28
Heater C o r e .................................................................. 1A-28
Blower Resistor U n i t ................................................... 1A-28
Muffler and Connector B lo c k ....................................... 1A-29
Kick Panel A ir Valve A c tu a to r.................................... 1A-29
Kick Panel A ir V a l v e ................................................... 1A-30
Plenum A ir V a lv e ......................................................... 1A-31
Compressor ............................................................... 1A-32
Wiring D i a g r a m ............................................................... 1A-33
Special T o o ls ..................................................................... 1A-34
Specifications ..................................................................
GENERAL
FOUR-SEASON SYSTEM
The Four-Season system uses an evaporator pressure
control known as the POA (Pressure Operated Absolute)
valve. The six-cylinder reciprocating compressor 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 con­
denser. All cooling system components are connected
by means of flexible refrigerant lines.
Both the heating and cooling functions are performed
by this system. Air entering the vehicle must pass
either through the cooling unit (evaporator) or through
the heating unit, or through both. The system is thus
referred to as a parallel 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 control,
is
automatically altitude compensated, and non­
repayable.
DESCRIPTION
F ig . 18 - Four-Season System Controls
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 20): Air,
either outside air, recirculated air or a mixture enters
the system and is forced through the system by the
blower.
The air passes by the temperature door and is directed
through the heating or cooling cores, or split to flow
through both. After flowing through the core or cores,
the air passes the outlets door which directs it to the
dash or floor outlets or both. Air directed to the dash
outlets is finally controlled by the position of the air
outlets. Air directed to the floor outlets passes the
defroster door which directs the air out the floor outlets,
the defroster outlets, or both.
Linkage is so designed that when the system controls
are calling for heat, air will enter the vehicle through the
floor distributor duct, and when the system controls call
for cooling, air will enter through the three dash outlets.
The side dash outlets may be rotated to provide either
soft, diffused airflow or spot cooling. Rotate half way to
shut off airflow. The barrel type outlet in the center of
the dash will direct air up or down or, if desired, shut it
off.
Controls
Full control of the Four-Season System is obtained
through the use of a single control panel (fig. 18). The
control levers make use of bowden cables to activate the
various doors and switches necessary for system opera­
tion.
Therefore, control adjustment is a matter of
properly setting these bowden cables. The following
paragraphs explain each control.
CHEVROLET TRUCK SERVICE MANUAL