Chevrolet 30 Series 1967 Service Manual page 40

HEATER AND AIR CONDITIONING 1A-12
" Outlet" Lever
This lever actuates an air diverter door within the duct
assembly which routes airflow when fully right (HEATER)
to the floor distributor ducts (for heater operation) or
when fully left (A/C) to the dash outlets (for cooling
operation).
Moving this lever toward the left from the HEATER
position will activate the compressor clutch switch and
set the cooling portion of the system in operation pro­
viding the FAN switch is turned on.
When the lever is moved fully toward the right (heating
position) the AIR control lever will automatically move
to the outside air position.
Temperature Lever
The "TEMPERATURE"
cable, actuates the door which controls outlet tempera­
ture. Since the heater core in this system is hot at all
times, this door is necessary to shut off the heat when
not wanted as well as to permit mixing of hot and cool
air to provide the desired conditioned air outlet tempera­
ture, whether during heating or cooling operations.
The temperature door directs the airflow through
either the heater core, the evaporator core or through
both. When the system is set for full cooling, all air
passes through the evaporator core. When warmer out­
let air is desired, the temperature door is moved by the
temperature lever so that some air passes through the
heater core. The warmed air mixes with the cooled air
PRECAUTIONS IN HANDLING REFRIGERANT-12
In any vocation or trade, there are established proce­
dures and practices that have been developed after many
years of experience. In addition, occupation 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.
Refrigerant-12 is transparent and colorless in both the
gaseous and liquid state. It has a boiling point of 21.7°F
below zero and, therefore, at all normal temperatures
and pressures it will be a vapor.
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
lever, through its bowden
GENERAL INFORMATION
The vapor is heavier
resulting in a higher outlet air temperature. In the full
HOT position, all air flows through the heater core.
cooler air, moving the lever toward COOL will send
some air through the evaporator core (inoperative when
the OUTLETS lever is set for heater operation) which in
effect bypasses the heater core resulting in less heat
output.
Air Control Lever
When the control is properly adjusted, full left position
("INSIDE") will supply 100% recirculated inside air, and
moving the lever to the word "OUTSIDE" will supply
100% outside air to the system.
trols a vacuum switch which in turn actuates an air inlet
door in the plenum below the air inlet grille and a
recirculating air door in the kick pad.
Defroster
As the Air control knob is moved to the right from the
"OUTSIDE" position toward the word DEFROSTER the
diverter door within the distributor duct moves to send a
portion of the airflow to the defroster ducts. Full "right"
position of the AIR knob, as indicated on the panel, is the
DE-ICE position which sends the total airflow to the
defroster ducts.
Fan Switch
The fan switch controls the operation of the three
speed blower motor.
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
accident 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.
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.
eyes are protected with goggles or glasses, no
serious damage can resu lt
For
Lever movement con­
The same gas will also attack
If the
Just remember, any
CHEVROLET TRUCK SERVICE M ANUAL