Chevrolet 10 Series 1968, Руководство по обслуживанию

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HEATER AND AIR CONDITIONING 1A-20
EVACUATING AND CHARGING PROCEDURES
AIR CONDITIONING SYSTEM CAPACITY
Refrigerant
Charge
Oil Charge
Four-Season System
3 lbs. 4 oz. 10 ozs. 525 viscosity
Evacuating and Charging Systen
1. Install charging station and p
under “ Purging the System",
while performing the following
2. After system has been purgec
PURGING THE SYSTEM
In replacing any of the air conditioning components the
system must be completely purged or drained of r e ­
frigerant. The purpose is to lower the pressure inside
the system so that a component part can be safely
removed.
1. With engine stopped, install high and low pressure
lines of Charging Station gauge set to the proper
high and low pressure gauge fittings. (See “ Install­
ing Charging Station to Check System Operation” ).
NOTE:
Before installing lines, be sure that all
four controls on the gauge set are closed.
2. Disconnect vacuum line at Charging Station vacuum
pump and lay end of line on a clean rag on the floor.
3. Crack open high (2) and low (1) pressure control
valves, and allow refrigerant to purge from system.
CA U TIO N : Do not open valves too much or
compressor oil may be discharged with the
refrigerant. Oil loss can be easily detected on
rag at discharge line.
EVACUATING AND CHARGING THE SYSTEM
GENERAL NOTE: In all evacuating procedures
shown below, the specification of 26-28 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, only 21 to 23 inches of vacuum can
normally be obtained.
Whenever the air conditioning system is open for any
reason, it should not be put into operation again until it
has been evacuated to remove air and moisture which
may have entered the system.
The following procedures are based on the use of the
J-8393 Charging Station.
Filling Charging Cylinder
1. Open control valve on refrigerant drum.
2. Open valve on bottom of charging cylinder allowing
refrigerant to enter cylinder.
3. Bleed cylinder valve on top (behind control panel) as
required to allow refrigerant to enter. When r e ­
frigerant reaches desired level (see “ A ir Condition­
ing System Capacity” ), close valve at bottom of cyl­
inder and be certain bleed valve is closed securely.
NOTE: It will be necessary to close bleed
valve periodically to allow boiling to subside to
check level in sight glass.
urge system as noted
, Refer to Figure 32
operation.
I, connect the vacuum
line to the vacuum pump, turn on pump and open
Vacuum Control Valve (3) - See “ General Note”
under “ Evacuating and Charging the System” . Con­
tinue to run pump for 15 minutes after the system
reaches 28-29 inches vacuum.
3. If 28-29 inches cannot be obtained, close Vaccum
Control Valve (3) and shut off vacuum pump. Open
Refrigerant Control Valve (4) and allow 1/2 pound of
R-12 to enter system. Locate and repair all leaks.
4. After evacuating for 15 minutes, add 1/2 pound of
R-12 to system as described in Step 3 above. Purge
this 1/2 pound and reevacuate for 5 minutes. This
second evacuation is to be certain that as much con­
tamination is removed from the system as possible.
5. Only after evacuating as above, system is ready for
charging. Note reading on sight glass of charging
cylinder. If it does not contain a sufficient amount
for a full charge, fill to the proper level.
6. With High and Low pressure Valves (1 and 2) open,
close Vacuum Control Valve (3) and open Freon
Control Valve (4). Operating the heater and air
conditioner blower with the controls set for cooling
will help complete the charging operation.
NOTE: If the charge will not transfer com­
pletely from the station to the system, close
the high pressure valve at the gauge set, set
the air conditioning controls for cooling, check
that the engine compartment is clear of ob­
structions, and start the engine. Compressor
operation will decrease the low side pressure
in the system.
System is now charged and should be performance
tested before removing gauges.
CHECKING OIL
In the six cylinder compressor it is not recommended
that the oil be checked as a matter of course. Gener­
ally, compressor oil level should be checked only where
there is evidence of a major loss of system oil such as
might be caused by:
• A broken refrigerant hose.
• A severe hose fitting leak.
• A very badly leaking compressor seal.
• Collision damage to the system components.
As a quick check on compressor oil charge, with the
engine off, carefully crack open the oil drain plug on the
bottom of the compressor. If oil comes out, the com­
pressor has the required amount of oil. To further check
the compressor oil charge, should the above test show
insufficient oil, it is necessary to remove the compressor
from the vehicle, drain and measure the oil.
Checking Compressor Oil Charge
1. Run the system for 10 minutes at 500-600 engine
rpm with controls set for maximum cooling and
high blower speed.
CHEVROLET TRUCK SERVICE MANUAL