Chevrolet Light Duty Truck 1973 Service Manual page 71

Refrigerant
Four-Season System
3 lbs.
(C-K Models)
Overhead System
5 lbs. 4 oz. 13 oz. 525 Viscosity
(C-K-G Models)
Floor Mounted System
3 lbs. 4 oz. 10 oz. 525 Viscosity
(G Models)
Dash Mounted Unit
(Motor Home Chassis) 3 lbs. 4 oz. 10 oz. 525 Viscosity
the compressor inlet line and the high pressure
fitting is on the compressor outlet line.
2. W ith the engine stopped, remove the caps from the
cored valve gauge fittings.
3. Install Gauge Adapters J-5420 and J-9459 onto the
high and low pressure lines of the Charging
Station.
4. Be certain all the valves on the Charging Station
are closed.
5. Connect the high pressure gauge line to the high
pressure fitting on the system.
6. Referring to Figure 49, turn the high pressure
control (2) one turn counterclockwise (open). Crack
open the low pressure control (1) and allow
refrigerant gas to hiss from the low pressure gauge
line for three seconds, and then connect the low
pressure line to the low pressure fitting on the
system.
When removing the gauge lines
W ARNING:
from the fittings, be sure to remove the
adapters from the system fittings rather than
the gauge lines from the adapter.
7. The system is now ready for purging or
performance testing.
PURGING THE SYSTEM
In replacing any of the air conditioning components, the
system must be completely purged or drained of
refrigerant. The purpose is to lower the pressure inside
the system so that a component part can be safety
removed.
1. With the engine stopped, install high and low
pressure lines of Charging Station gauge set to the
proper high and low pressure gauge fittings (See
"Installing The Charging Station").
Before installing lines, be sure that
CAUTIO N:
all four controls on the gauge set are closed.
2. Disconnect vacuum line at Charging Station
Oil Charge
Charge
10 oz. 525 Viscosity
HEATER A N D AIR C O N D IT IO N IN G
REFRIGERANT LINE
LOW PRESSURE ACCUMULATOR (CONDENSER TO
Fig. 49--Charging Schematic-C-K Truck Shown
vacuum pump and put the line in a covered can as
shown in Figure 50.
NOTE: An empty 3 lb. coffee can with a
plastic cover which has been cross-slit (X'ed),
to allow hose entry, works well for this
purpose.
3. Fully open high (2) and low (1) pressure control
valves, and allow refrigerant to purge from system
at a rapid rate into the covered can.
4. Oil loss will be minimal. It may be added to the
system during evacuation as described later.
5. Toward the end of the purge stage, Tool J-24095
should be flushed with refrigerant to eliminate
possible contamination.
a. Disconnect refrigerant line at supply tank.
b. Flush Tool J-24095 by cracking open valve on
refrigerant tank. After flushing for approx­
imately three seconds, close valve.
c. Temporarily refasten the tool.
d. Reconnect refrigerant line to supply tank.
EVACUATING AND CHARGING THE
SYSTEM
GENERAL NOTE: In all evacuating procedures
shown below, the specification of 28-29 inches of
Mercury vacuum is used. These figures are only
attainable at or near Sea Level Elevation. For each
1000 feet above sea level where this operation is
being performed, the specifications should be
lowered by 1 inch. Example: at +5000 ft. elevation,
1A-45
M|G n PRESSURE
LIGHT DUTY TRUCK SERVICE MANUAL