cooling CHEVROLET CAMARO 1967 1.G Chassis Workshop Manual
[x] Cancel search | Manufacturer: CHEVROLET, Model Year: 1967, Model line: CAMARO, Model: CHEVROLET CAMARO 1967 1.GPages: 659, PDF Size: 114.24 MB
Page 16 of 659
LUBRICATION 0-14
SAE 5W-30 oils may be used during periods when
temperatures of 32° and below are to be expected.
Types of Oils
In service, crankcase oils may form sludge and varnish
and under some conditions, corrosive acids unless pro-
tected against oxidation.
To minimize the formation of these harmful products
and to assure the use of oil best suited for present day
operating conditions, automobile manufacturers have de-
veloped a series of sequence tests designed to evaluate
the ability of any oil to properly lubricate automobile
engines.
It is recommended that only those oils which are
certified by their suppliers as meeting or exceeding the
maximum severity requirements of these sequence tests
(or GM Standard 4745-M) be used in Chevrolet engines.
Certified sequence tested oils will be described as such
on their containers.
Maintaining Oil Level
The oil gauge rod is marked "Full" and "Add Oil."
These notations have broad arrows pointing to the level
lines.
The oil level should be maintained between the
two lines, neither going above the "Full" line nor under
the "Add Oil" line. DO NOT OVERFILL. After operating
vehicle allow a few minutes for oil to return to crankcase
before checking oil level.
Check the oil level frequently and add oil when
necessary.
Oil and Filter Change Intervals
NOTE:
Under prolonged dusty driving condi-
tions,
it is recommended that these operations
be performed more often.
OIL
To insure continuation of best performance, low main-
tenance cost and long engine life, it is necessary to
change the crankcase oil whenever it becomes contami-
nated with harmful foreign materials. Under normal
driving conditions draining the crankcase and refilling
with fresh oil every 60 days or every 6000 miles which-
ever occurs first, is recommended.
It is always advisable to drain the crankcase only after
the engine has become thoroughly warmed up or reached
normal operating temperature. The benefit of draining is,
to a large extent, lost if the crankcase is drained when
the engine is cold, as some of the suspended foreign
material will cling to the sides of the oil pan and will not
drain out readily with the cold, slower moving oil.
OIL FILTER
Change engine oil filter every 6000 miles or every 6
months, whichever occurs first.
NOTE:
For Vehicles in heavy duty operation
involving continuous start-stop or prolonged idl-
ing, engine oil should be changed after 2500-
3000 miles of operation. The filter should be
changed after 5000-6000 miles of operation.
Crankcase Dilution
Probably the most serious phase of engine oil deterio-
ration is that of crankcase dilution which is the thinning
of the oil by fuel vapor leaking by pistons and rings and
mixing with the oil and by condensation of water on the
cylinder walls and crankcase.
Leakage of fuel, or fuel vapors, into the oil pan occurs
mostly during the "warming up" period when the fuel is
not thoroughly vaporized and burned. Water vapor enters
the crankcase through normal engine ventilation and
through exhaust gas blow-by. When the engine is not
completely warmed up, these vapors condense, combine
with the condensed fuel and exhaust gases and form acid
compounds in the crankcase.
As long as the gases and internal walls of the crank-
case are hot enough to keep water vapor from con-
densing, no harm will result. However, when the engine
is run in low temperatures moisture will collect and
unite with the gases formed by combustion resulting in
an acid formation. The acid thus formed is likely to
cause serious etching or pitting which will manifest itself
in excessively rapid wear on piston pins, camshaft
bearings and other moving parts of the engine, oftentimes
causing the owner to blame the car manufacturer or the
lubricating oil when in reality the trouble may be traced
back to the character of fuel used, or a condition of the
engine such as excessive blowby or improper carburetor
adjustment.
Automatic Control Devices to Minimize
Crankcase Dilution
All engines are equipped with automatic devices which
aid greatly in minimizing the danger of crankcase
dUution.
The thermostat, mounted in the cylinder head water
outlet, restricts the flow of water to the radiator until a
predetermined temperature is reached, thus minimizing
the length of time required to reach efficient operating
temperature, reducing the time that engine temperatures
are conducive to vapor condensation.
A water by-pass is included in the cooling system,
utilizing a hole in the front of, the cylinder block. This
allows a limited circulation of coolant, bypassing the
thermostat until thermostat opening temperatures are
reached. This system provides a uniform coolant tem-
perature throughout the engine, eliminating localized
hot-spots, improving exhaust valve life, provides fast
warmrup of lubricating oil and fast temperature rise in
the coolant which provides fast heater operation in cold
weather.
A thermostatic heat control on the exhaust manifold
during the warming up period, automatically directs the
hot exhaust gases against the center of the intake mani-
fold, greatly aids in proper vaporization of the fuel.
An automatic choke reduces the danger of raw or
unvaporized fuel entering the combustion chamber and
leaking into the oil reservoir.
An.
efficient crankcase ventilating system drives off
fuel vapors and aids in the evaporation of the raw fuel
and water which may find its way into the oil pan.
CRANKCASE BREATHER CAP
Clean and re-oil at every oil change..
CHEVROLET CHASSIS SERVICE MANUAL
Page 29 of 659
HEATER AND AIR CONDITIONING 1A-6
CHEVROLET SHOWN AS TYPICAL
Fig.
8—Heater Hose Routing (Chevrolet Shown as Typical)
cables, defroster hoses and the
place and install all at-
4.
5.
6.
Attach all bowden
wiring connector.
Set heater assembly into
taching nuts and screws.
Attach inlet and outlet hoses.
Replace glove box and glove box door.
Refill cooling system.
Defroster Duct
Installation of the defroster duct as used in Chevy H
vehicles is illustrated in Figure 14.
Blower Motor
Replacement
1.
Remove the heater assembly from the firewall.
Remove the five screws attaching the motor and
blower to the heater assembly.
2.
Remove the retainer attaching blower to the motor
shaft.
3.
Replace blower on new motor assembly, balance and
reinstall into heater assembly.
Fan Control
Replacement
1.
Remove the screws at the dash lower edge which
retain the control assembly and lower the assembly.
2.
Disconnect the blower harness connector and remove
the switch retaining screws and switch.
3.
Install the replacement switch with the nylon bearing
inserted into the AIR - FAN lever slot.
4.
Connect the blower harness connector and remount
the control assembly in the dash.
CORVETTE
Blower Assembly
Removal
1.
Remove the radiator supply tank from its retaining
straps and move it out of the way, then disconnect
the battery positive cable.
NOTE:
It is not necessary to drain the radiator.
2.
Remove the connectors from the blower motor.
3.
Scribe or chalk a mark on the blower motor mount-
ing plate and blower assembly.
4.
Remove the five screws retaining the blower mount-
ing plate to the blower inlet assembly.
Withdraw the blower assembly from the inlet
5.
assembly.
Disassembly
Remove the blower wheel from the motor by removing
the nut and tapping the motor shaft with a soft hammer.
Installation
1.
Assemble the blower to motor and using the scribe
mark, properly position the blower assembly on the
inlet assembly and install the five screws.
2.
Replace the electrical connectors on the blower
motor.
3.
Replace the radiator supply tank and the battery
positive cable.
Blower and Air Inlet Assembly
Removal
1.
Drain the radiator.
2.
Remove the radiator supply tank from its retaining
straps and swing it out of the way.
3.
Remove the battery.
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 39 of 659
HEATER AND AIR CONDITIONING 1A-16
EVAPORATOR
CORE
\
BLOWER AND AIR I
INLET ASSEMBLY •
AIR
DOOR
OUTSIDE AIR FROM COWL VENT
DEFROSTER
DUCT
DEFROSTER
DOOR
COOLED AIR
OUTLETS
Fig.
25—Airflow—Four-Season (Cheyelie)
will be hot at all times. When, during cooling operations,
the air is cooled by the evaporator to below comfort
level, it is then warmed by the heater to the desired
temperature; during "heating only" operations the evap-
orator will not be in operation and ambient air will be
warmed to the desired level in the same manner. 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
Four-Season System (Chevrolet, Camaro)
Full control of the Four-Season System is obtained
through the use of a single control panel (fig. 26). The
control knobs 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.
Temperature Lever
The TEMPERATURE lever controls temperature door
position, compressor operation, and air selector door
position. When the lever is in the OFF position, the sys-
tem is totally inoperative; airflow is shut off, the fan
switch will not operate the blower, and the compressor
is off. In the VENT position, the air selector door is in
the "outside air" position and the blower is powered at
low speed. At any lever position other than OFF, the
blower will be powered at low, however, blower speed
may be increased by moving the FAN switch. When the
Fig.
26—Chevrolet Four-Season Controls
Fig.
27—CheveNe Four-Season Controls
CHEVROLET CHASSIS SERVICE MANUAL
Page 43 of 659
HEATER AND AIR CONDITIONING 1A-20
and its resistance is decreasing. In the HI FRONT
position, two thermistors (the master delay and high
blower delay thermistors) are warming. The air
door is in recirculation position until the engine
coolant reaches 75 degrees.
2.
The coolant reaches then 75 degrees and the thermal
vacuum valve opens applying vacuum to the air door
to admit outside air (unless the temperature dial is
set for cooling). Ram air will flow through the sys-
tem when the car is moving.
3.
Next, the master delay thermistor attains the tem-
perature at which it will pass sufficient current to
close the circuit through the master delay relay.
The relay circuit powers the blower motor at 9 volts.
4.
If the control is in the HI FRONT position, the high
blower delay thermistor will close the circuit
through the high blower relay which supplies full
available voltage to the blower motor. This function
occurs after the master delay thermistor has taken
effect because the high blower delay thermistor
uses the master delay type thermistor with a 10 ohm
1/4 watt resistor connected in
.
series. The nigh
blower delay thermistor must then warm to a higher
temperature than the master delay thermistor before
its resistance (plus that of the 10 ohm resistor)
drops enough to actuate the high blower relay.
5. If the controls are set for DE ICE, full outside air
and full voltage to the blower motor are effective
immediately regardless of temperatures or elapsed
times o
In accomplishing automatic control, the system follows
three steps to transform an electronic signal into me-
chanical energy through which the control is achieved.
Electronic Circuit
Two temperature sensors (Thermistors), and the duct
potentiometer connected in series, are located so as to
sense the temperature of the outside air, inside air and
system output air. The resistance of each sensor will
vary according to its temperature. The control head
temperature dial varies in resistance as it is adjusted by
the operator to suit his comfort requirements. The
resistance of the temperature dial control is applied
directly to the amplifier and is not in series with the
sensors and duct potentiometer. Thus temperature dif-
ferences in the sensor string plus the requirements fed
into the system by the operator cause changes in total
circuit resistance which allow a varying voltage flow
through the circuit.
Changing the Electronic Signal to Electrical Voltage
This minute voltage flow from the sensor string -
temperature dial circuit - is fed into the amplifier where
it is transformed into a usable amplifier output voltage,
the strength of which is determined by the strength of the
original amplifier input signal. This voltage is then
supplied to the transducer.
Changing the Electrical Voltage to a Vacuum Signal
Amplifier output voltage, varying according to tem-
perature requirements, is converted by the Transducer
into a modulator transducer output vacuum. This modu-
lated vacuum is applied to the Power Servo.
Changing the Vacuum Signal to Mechanical Energy
The Power Servo, controlled by the modulated Trans-
ducer output vacuum, operates the vacuum electrical and
mechanical components of the system as required to
provide automatic control of system operation.
Other major system components are mounted con-
ventionally in the engine compartment. Underhood com-
ponents and system airflow remain much the same as in
the Four-Season system except for the addition of the
automatic control provisions. The system operates on
100%
outside air, a mixture of outside and inside air, or
100%
recirculated air depending on the demands of the
system. The diaphragm operated .air selector door will
modulate outside air to the system during maximum air
conditioning requirements when the control unit is in
"Hi Front" position. Control of the blower is also com-
pletely automatic and dependent upon system demands.
Controls
The Comfortron controls the Chevrolet air conditioner
and heater in such a precise manner that the automobile
temperature remains relatively constant under all driving
conditions. By adjusting the thumb wheel on the Control
Head to any temperature desired between 65° and 85° F.
(See Figure 27) the automatic system will adjust the in-
car temperature even though the outside weather condi-
tions may vary considerably. The system will provide
maximum capacity for heating or cooling until the in-car
temperature reaches the pre-set Control Head Tempera-
ture. Where cooling is required, the system will start
immediately upon being turned "ON". During marginal
ambient temperatures the system will not always start
at the highest blower speeds of the control setting.
Therefore, occasionally the system can't be heard
starting*
Five over-riding functions are available so that special
conditions can be handled. Each Control Head function
will be discussed in detail below:
"Off" Position
In the "Off" position, the blower is turned off and the
outside air door is closed. No outside air should enter
the automobile.
"Lo Front" Position
The blower has five low to moderate speeds; Hi, M3,
M2,
M1 and Lo. The blower voltage will shift as directed
by the automatic controls. The "Lo Front" position
provides a quieter mode of automatic operation due to
reduction of blower noise.
"Hi Front" Position
The "Hi Front" position provides five high blower
speeds as called for by the automatic controls: The use
of the "Hi" blower speed results in a rapid cool down in
hot weather and rapid heating during cold weather. As
the in-car temperature approaches the temperature set-
ting on the Comfortron Control Head, the blower speed
will change, provided mild outside temperatures are
experienced. During very hot or cold weather, the blower
will reduce its speed only to the point where it is still
capable of maintaining the correct inrcar temperature.
"Rear" Position
The "Rear" position provides five high blower speeds.
The automatic controls select these speeds and blend the
discharge air to the proper temperature. By the use of
high blower speeds, increased airflow is obtained for
better rear seat passenger comfort.
CHEVROLET CHASSIS SERVICE MANUAL
Page 44 of 659
HEATER AND AIR CONDITIONING 1A-21
"De-Fog"
Position
In the event that the front windshield should require
removal of a fogging condition, the owner at his option
may direct air to the windshield. The "De-Fog" position
directs part of the air to the windshield while retaining a
certain amount through the floor outlets. The temper-
ature of the air remains the same as it was prior to the
control being placed in the "De-Fog" position. Five
blower speeds are available. The temperature of the air
and the blower speed are selected by the automatic
controls and are dependent upon the in-car temperature.
"De-Ice" Position
The "De-Ice" position provides full heat with "Hi"
blower directing the entire airflow to the windshield to
melt ice. The automatic controls are completely defeated
and as a result, full heat with "Hi" blower are the only
conditions that can be received. The system will turn on
immediately in this position even though the engine
coolant might be cold.
General Information
Three start up conditions can be achieved with
Comfortron.
Weather
Cold
Method of Starting System
System starts as soon as engine coolant is
hot.
Hot System starts immediately when AC is
required.
Any System starts immediately in "De-Ice"
position.
UNIVERSAL SYSTEM
A self-contained unit, the dealer installed Universal
System operates on recirculated air only and entirely
independent of the vehicle heater. Recirculated inside air
is drawn into the unit, passed through the evaporator core
and into the car through the adjustable outlets in the
evaporator case. The entire unit mounts compactly
beneath the dash. Temperature control is by means of a
thermostatic switch.
The compressor used with the Universal System is
identical to that used for the Four-Season system except
for displacement. Underhood components are similar in
placement to the Four-Season system.
Controls
Universal system controls are the AIR knob controlling
the three speed blower motor switch and the TEMP knob
which controls the setting of the thermostatic switchi
Switch adjustment is covered elsewhere in this section.
When operating this system the Heater must be fully off.
CHEVY II ALL-WEATHER SYSTEM
The Chevy n All-Weather Air Conditioning System,
Figure 33, operates in conjunction with the heater to
provide a complete air conditioning system operating on
either outside air, recirculated air or a combination of
both. The cooling unit attaches to the heater distributor
and utilizes the heater blower. Several controls allow
full use of either the heating or cooling features of the
system. During marginal weather, it is possible to pro-
vide heated air at floor level and cooled air at breath
level.
A schematic view of the air conditioning underdash
components is provided in Figure 34 to aid in under-
standing airflow and control operation.
The evaporator assembly, located in the passenger
compartment attached directly to the heater distributor,
contains the evaporator core, expansion valve, thermo-
static switch and the air conditioning "ON" knob. The
thermostatic switch, utilized as the cooling control, feels
the temperature of the cooled air leaving the evaporator
core and turns the compressor on and off in accordance
with cooling needs. Refrigerant lines connect the evap-
orator assembly to the other system components located
in the engine compartment.
The six cylinder air conditioning compressor, com-
pletely field serviceable, is bracket-mounted to the
engine and is belt driven from the crankshaft pulley. A
muffler assembly, designed to eliminate compressor
pulsations is an integral part of the compressor con-
nector block. The condenser is mounted on the radiator
support just ahead of the engine radiator. The receiver-
dehydrator, with its sight glass, is located on the right
fender skirt.
Controls
Control of the air conditioning system is achieved
through the use of the heater control on the instrument
panel as well as the two knobs located on the air condi-
tioning unit itself (fig. 35).
Air Conditioning "ON" Knob
Labeled "Pull for Air Cond.", this knob diverts air-
flow from the floor distributor and through the air condi-
tioning unit. Initial movement of this knob also actuates a
switch, located at the damper door, which energizes the
compressor clutch thus putting the system into operation
and under the control of the thermostatic switch.
Temp-Cool Knob
This knob controls the thermostatic switch. Turn the
knob clockwise for more cooling, counter-clockwise for
less cooling.
Air Lever
This lever actuates the damper within the assembly
which chooses between recirculated air or outside air.
Fig.
31-Universal Air Conditioning Unit
CHEVROLET CHASSIS SERVICE MANUAL
Page 45 of 659
HEATER AND AIR CONDITIONING 1A-22
RECEIVER &
OEHYDRATOR ASM
HOSES
CONDENSER
ASM.
Fig.
32—Universal System Components
Full right position will supply 100% outside air (for
heater operation) to the system while full left position
will provide 100% inside (recirculated) air for cooling
operation during city driving to shut out dust and fumes.
Recommended setting of this lever for most air con-
ditioning operations is about 1/4" to the right. This will
provide a mixture of recirculated air and outside air.
Fan Switch
The switch operates the three-speed blower motor.
Temperature Lever
This lever operates the damper door which controls
heater outlet temperature in the same manner as de-
scribed in the heater section.
"Two-Level"
Temperature Control
By moving the temperature lever to provide the desired
temperature on the floor, pulling the "Air Cond— Pull"
knob out halfway and moving the "Air" lever fully right
and setting the "Temp-Cool" knob for the desired breath
level temperature, "two-level" temperature control can
be maintained. This is especially desirable during
"marginal" weather conditions.
CORVETTE
The Corvette Four-Season Air Conditioning System, by
combining heating and cooling functions in a single unit,
provides maximum driving comfort during every season
of the year. Cooling and heating cores are mounted in
this "reheat" system in such a way that full outside air,
full recirculated air or a mixture, passes from the three-
speed blower through the evaporator (cooling) core and
then through and/or around the heater core. If the sys-
tem is not calling for heat all of the air flow will bypass
the heater core.
The cooling components of the system include the
compressor, condenser, receiver-d,ehydrator and evap-
orator together with the expansion valve and suction
throttling valve, all installed compactly beneath the
hood. The evaporator provides maximum cooling of the
system airflow when cooling is required. Cool airflow
is tempered by mixing warm air from the heater with
the cooled air from the evaporator. The PDA valve con-
trols evaporator pressure so that the unit may hold the
lowest pressure possible without danger of core freeze
up.
CHEVROLET CHASSIS SERVICE MANUAL
Page 47 of 659
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
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HEATER AND AIR CONDITIONING 1A-25
Fig.
37—-Corvette Four-Season System Components
pass through the system. For heating operations it is
suggested that Ml outside air (knob Mly OUT) be used.
For cooling operations under extreme heat conditions
push knob fully in (recirculated inside air); under moder-
ate temperature conditions pull the knob out to the detent
position (a misxture of outside air and inside air); and
under mild temperature conditions the knob may be
pulled fully out (outside air).
After the AIR PULL knob is set to permit air to pass
through the system, the knob may be rotated to control
the three-speed blower. When the AIR COND.-PULL
knob is pulled out the low blower is in operation. Select
higher speeds as desired.
Temperature Adjustment
The COOL IN-HOT PULL knob controls the air output
temperature during both heating and cooling operations.
A vacuum switch (operated by the temperature door
actuating cam) controls a vacuum operated water valve
which allows engine coolant to flow through the heater
core only when this knob is pulled out.
During heating operation cold ambient air enters the
conditioner, passes through the inoperative cooling core
and then passes through and around the heating core
(the final mixture of hot and cold air being determined
by the control knob - temperature door setting) and then
enters the car.
Cooling operation is exactly the same except that the
cooling core (evaporator) will be in operation at Ml
capacity, removing as much heat and humidity as pos-
sible from the warm ambient air flowing through it.
The COOL IN-HOT PULL knob may then be pulled out
as needed to temper this maximum cold airflow should
it become necessary.
Defroster Control
This control acts to divert heated air from the floor
distributor duct into the defroster duct for windshield
defogging, defrosting and deicing operations. A detent
is built into the defroster linkage to indicate the setting
at which a small portion of the heater air will be con-
tinaully passed over the windshield, thus keeping it clear.
Operating Instructions
Remember that the air conditioning system may be
used for heating or cooling during any season of the
year to provide just the desired comfort conditions.
Cooling
1.
"Air Cond-Pull". This knob should be pulled fully
out.
2.
"Cool In-Hot Pull". This knob should be pushed
fully in for maTriTr»"Tn cooling. Pulling out the knob
as required will mix warm air with the cool air to
temper the cool air output.
3.
"Air Pull-Fan". Set this knob fully in during ex-
treme heat conditions; at the detent position during
moderate temperature conditions; fully out during
mild temperature conditions or whenever tempering
of the cooled air flow is necessary. Turn the knob
CHEVROLET CHASSIS SERVICE MANUAL
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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