Chevrolet Light Duty Truck 1973 Service Manual page 79

3. The system will also indicate a low refrigerant
charge by bubbles occurring in the sight glass.
ENGINE IDLE COMPENSATOR
This additional aid to prevent stalling during prolonged
hot weather periods is included with all air conditioned
PREPARING SYSTEM FOR REPLACEMENT
OF COMPONENT PARTS
Air conditioning, like many other things, is fairly simple
to service once it is understood. However, there are
certain procedures, practices and precautions that should
be followed. For this reason it is strongly recommended
that the preceding information in this section be studied
thoroughly before attempting to service the system.
G reat emphasis must be placed upon keeping the system
clean. Use plugs or caps to close system components and
hoses when they are opened to the atmosphere. Keep
your work area clean.
In removing and replacing any part which requires
unsealing the refrigerant circuit the following operations,
which are described in this section, must be performed
in the sequence shown.
1. Purge the system by releasing the refrigerant to the
atmosphere.
2. Remove and replace the defective part.
3. Evacuate, charge and check the system.
Always wear protective goggles
W ARNING:
when working on refrigeration systems.
Goggles J-5453 are included in the set of air
conditioning special tools. Also, beware of the
danger of carbon monoxide fumes by
avoiding running the engine in closed or
improperly ventilated garages.
FOREIGN MATERIAL IN THE SYSTEM
Whenever foreign material is found in the system, it
must be removed before restoring the system to
operation.
In the case of compressor mechanical failure, perform
the following operations:
1. Remove the compressor.
2. Remove the receiver-dehydrator or expansion tube
and discard the unit.
3. Flush the condenser to remove foreign material
which has been pumped into it.
4. Disconnect the line at the evaporator core inlet (C-
K Four-Season System) or inlet line to the
expansion valve (except C-K Four-Season System).
GENERAL REPAIR PROCEDURES
HEATER A ND AIR C O N D IT IO N IN G
vehicles. The idle compensator is a thermostatically
controlled air bleed which supplies additional air to the
idle mixture. On V-8 engines, with factory installed air
conditioning systems, the compensator is located within
the carburetor and is accessible when the engine air
cleaner is remove.
Inspect the expansion tube or inlet screen of the
expansion valve for the presence of metal chips or
other foreign material. If the tube or screen is
plugged, replace it. Reconnect the line to the
evaporator core or expansion valve.
5. Install the replacement compressor.
6. Add the necessary quantity of oil to the system (one
fluid ounce because of receiver-dehydrator replace­
ment plus the quantity needed for the replacement
compressor - see "Checking Compressor Oil
Charge" under "Checking Oil."
7. Evacuate, charge and check system.
REFRIGERANT LINE CONNECTIONS
" 0 " Rings
Always replace the "O " ring when a connection has been
broken. When replacing the "O " ring, first dip it in clean
refrigeration oil. Always use a backing wrench on "O "
ring fittings to prevent the pipe from twisting and
damaging the "O " ring. Do not overtighten. Correct
torque specifications are as follows:
Where steel to aluminum connec­
CAUTION:
tions are being made, use torque for aluminum
tubing.
Metal Thread and
Tube
Fitting
O.D. Size
7/16
1/4
3/8 5/8
3/4
1/2
5/8 7/8
3/4 1-1/16
Foot Pounds
*
Hose Clamps
When hose clamp connections are encountered, special
procedures are necessary for both removal and
installation.
Removal
1. Carefully, with a sharp knife, make an angle cut in
1A-53
Steel Alum.
Tubing Tubing
Torque* Torque*
13 6
33 12
33
n
33 20
33 25
LIGHT DUTY TRUCK SERVICE MANUAL