CHEVROLET CAMARO 1967 1.G Chassis Service Manual
Manufacturer: CHEVROLET, Model Year: 1967, Model line: CAMARO, Model: CHEVROLET CAMARO 1967 1.GPages: 659, PDF Size: 114.24 MB
Page 41 of 659
HEATER AND AIR CONDITIONING 1A-18
HIGH BLOWER
i DELAY RELAY
AMBIENT-SUN
SENSOR AND
COMPRESSOR SWITCH
Fig. 29—Comfortron Engine Compartment Components
COMFORTRON SYSTEM
The Chevrolet Comfortron Air Conditioning System is
basically the same as the Chevrolet Four-Season system
but with the additional feature of completely automatic
control. See Figures 28, 29 and 30 for views of the
Comfortron system. To the customer, the most notice-
able difference between the two systems, will be in the
control panel. In place of the three-lever/one-switch
panel of the Four-Season system, the Comfortron has a
single control lever plus a temperature dial similar to
that found in a home thermostat. After the dial is set to
the desired temperature indication and the lever is moved
to place the system in operation, the Comfortron will
automatically control the heating and air conditioning
functions to maintain the selected interior temperature
regardless of changes in outside air temperatures.
Most Comfortron parts are located in the passenger
compartment, (fig. 28)
Jn-Car Sensor
The function of the in-car sensor is to determine the
temperature of the interior of the automobile. It is
located beneath the overhang of the instrument panel.
Feedback Potentiometer
The feedback potentiometer indicates to the amplifier
system the position of the temperature door.
Control Head
A thumb wheel is provided to select the desired in-car
temperature. A control lever performs the following
functions:
1.
Operates a switch that allows the customer to select
the type of blower program desired.
2.
Operates the control head vacuum switch except
when the TEMPERATURE lever is in the OFF
position, thus programming the vacuum system.
3.
Operates the defroster through the control head
vacuum switch. The defroster door is partially
opened in the "DE FOG" position, and fully open in
the "DE ICE" position.
A two transistor amplifier is located on the bottom
side of the control head. It receives information from
the sensors, and in turn operates the transducer.
Fig. 30—Comfortron Control
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HEATER AND AIR CONDITIONING 1A-19
Transducer
The transducer will produce a vacuum output that is
completely adjustable by varying the input voltage which
is provided by the amplifier. An increase in the applied
voltage results in a reduced vacuum output.
Power Servo
The power servo receives a vacuum signal from the
transducer, and it is capable of assuming any position
that is called for by the sensors, amplifier, and trans-
ducer. The power servo performs the following functions:
1.
Positions the temperature mix door via the tern-
perature door link. The position of this door~"de-
termihes the portions of hot and cold air being
blended and discharged into the car.
2.
Operates the power servo vacuum valve which de-
termines the air flow paths for heating and air
conditioning.
3.
Contains a printed circuit board which controls the
blower speed. The power servo position determines
the blower speed, but the control lever switch can
override the blower program depending upon the
customer's preference.
4.
Contains the "Hi" blower delay thermistor and the
"master delay thermistor".
Outside Air Diaphragm
When there is no vacuum applied to the hose, the out-
side air door is closed under spring tension. With the
door closed, air is taken from the inside of the auto-
mobile and re-circulated. Applying vacuum to the dia-
phragm opens the door for outside air.
Mode Door Diaphragm
Located behind the duct work, the mode door diaphragm
directs the air flow out either the air conditioning outlets,
the heater floor outlet, or both the heater and air con-
ditioning outlets. This is a push-pull type diaphragm
actuated by vacuum through two hoses and controlled by
the power servo vacuum switch.
Defroster Door
The defroster door is in the defog position until vacuum
is applied to the actuator to obtain either full heat or full
de-ice position.
High Blower Delay Thermistor
The high blower delay thermistor is located on the
power servo housing under the power servo vacuum valve
and printed circuit board assemblies. The function of the
thermistor is to operate the blower at a reduced speed
when the control is in the HI FRONT position until the
residual cold air is discharged from the duct work. This
function occurs when the blower first comes "on" in cold
weather.
Vacuum Tank
During heavy acceleration, the vacuum supply from
the carburetor drops. The vacuum tank, using a^ check
valve, stores vacuum so that under these conditions
vacuum will be available for the Comfortron.
Thermal Vacuum Valve (Hot Water Vacuum Switch)
When engine coolant temperature reaches 75°F, the
valve opens and supplies vacuum to the outside air door
if the system is calling for outside air.
Master Delay Thermister
This thermistor delays the initial operation of the
blower when the system is in the heat mode. In cold
weather this allows outside ram air to flow through the
system thereby purging the cold air in the ducts gradually
until the coolant reaches about 105°F. Then, the termis-
tor passes enough current to energize the master delay
relay which powers the blower at about nine volts.
Vacuum Relay Valve
This relay valve will shut off transducer vacuum to the
power servo whenever the vacuum from the engine intake
manifold falls below the vacuum in the power servo
supply line (engine stopped or operating at low manifold
vacuum). This causes the power servo to be held in
position when the vacuum supply falls too low to maintain
servo control.
Vacuum Bleeder
A vacuum bleeder insures that the outside air door will
close (diaphragm will bleed down) after the system has
been shut down. This prevents outside air from entering
when starting the system on a cold day before the engine
coolant temperature reaches 75°F.
Sun—Ambient Sensor
The sun-ambient sensor measures the temperature of
the air entering the air intake grille in front of the wind-
shield. The sensor is exposed to sun light so that it can
lower the in-car temperature slightly when the sun
is shining.
Ambient Switch
The ambient switch operates the air conditioning com-
pressor clutch. When the outside temperature is above
40° F. the switch will be closed and the compressor will
be running. This switch is included as| part of the sun-
ambient sensor assembly, but operates independently.
Resistor Assembly
The blower resistors are located in the evaporator
housing. The printed circuit board switch in the power
servo determines which of the resistors is being used,
and as in conventional systems, the resistors control the
blower speed.
System Operation
When starting the Comfortron System in cold weather,
the following sequence of events occurs:
1.
Initially the system is inoperative. In LO FRONT
position the master delay thermistor is warming
(self-heating because current is flowing through it)
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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.
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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
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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.
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HEATER AND AIR CONDITIONING 1A-23
DEFROSTER
RECEIVER
DEHYDRATOR
EVAPORATOR
Fig.
33—All Weather System Components (Chevy II)
DEFROSTER OUTLETS
OUTSIDE
AIR
FROM PLENUM DUCT
BLOWER
--—-.
DEFROSTER
DOOR
HEATER OUTLET
AIR CONDITIONER "ON" DOOR
EVAPORATOR CORE
COLD
HEATER
CORE
AIR CONDITIONER
OUTLETS
AIR CONDITIONING
CONTROLS
AIR CONDITIONING
"ON"
KNOB
\ AIR DOOR
^CIRCULATED
m
AIR-FAN KNOB-
HEAT KNOB
HEAT DOOR
AIR
HEATER CONTROLS
IMJLJLII
""" L
—Mwm \
' / DASH PANEl
KNOB
DEFROSTER KNOB
Fig.
34-AH Weather System Schematic
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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
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Page 48 of 659
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
Page 50 of 659
HEATER AND AIR CONDITIONING 1A-27
POA SUCTION
THROTTLING
RTJING
^EXTERNAL
EQUALIZER LINE
COMPRESSOR
(Operates
continually
while system
is in operation)
M
H. P.
VAPOR
OIL BLEED LINE
SIGHT
,n
RECEIVERS
DEHYDRATOR
/
CONDENSER
EVAPORATOR
H.
P.
LIQUID
H
L. P.
LIQUID H] L.
P.
VAPOR
@ H. P.
POWER ELEMENT
III
•••••Mi
IM •—>•••—^
Fig.
38—Cycle
of
Operation—Four-Season and Comfortron
LINE
TO
COMPRESSOR
CLUTCH
THERMOSTATIC
SWITCH
v
CAPILLARY
* TUBING
EXPANSION
VALVE
SIGHT
GLASS
COMPRESSOR
(Operation
controlled
by thermostatic
switch)
I
H. P.
VAPOR
1
H. P.
LIQUID
aiJJ>1Tg.VW
RECEIVER
DEHYDRATOR
CONDENSER
EVAPORATOR
AVPSty>t*i"^if^
L.
P.
LIQUID
L.
P.
VAPOR
H.
P.
VAPOR POWER ELEMENT
Fig.
39-Cyc!e
of
Operation—Universal and All Weather
CHEVROLET CHASSIS SERVICE MANUAL