Evacuating And Charging The System; Adding Oil; E V Acu Ating An D C H A Rg In G The S Y S T E - Chevrolet CHEVY VAN G10 SERIES Service Manual

A IR C O N D ITIO N IN G 1A-18

EVACUATING AND CHARGING THE SYSTEM

G E N E R A L N O T E : 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 perform ed, the specifications should be low ­
ered by 1 inch. Example:
only 23 to 24 inches o f vacuum can norm ally be
obtained.
Whenever the air conditioning system is open for any
reason, it should not be p u t in to operation again until it has
been evacuated to remove air and m oisture w hich may have
entered the system .
The following procedures are based on the use o f the
J-8393 Charging S tation.

Adding Oil

If necessary, refrigeration oil may be added to the system
by the following m ethod:
1. Install Charging S tation and purge system as previously
described.
2. A fter system has been purged, connect the vacuum line
to the vacuum pum p.
3. Measure oil loss collected as a result o f purging the
system .
a. Disconnect low pressure line at fitting. Install Tool
J-24095 (w ith valve closed) o n to low pressure line
fitting. Insert pick-up tube into graduated container
o f clean refrigeration oil (Fig. 26).
N O T E : Tool J-2 40 95 will hold 1 /2 o f an ounce o f
oil in the tool itself. So if 1 oz. has to be added, the
level of the oil in the b ottle should decrease 1 -1 /2
ounces to add 1 oz. to the system.
J - 2 4 0 9 5
TO LOW
PRESSURE
CHARGING STATION
HIGH PRESSURE LINE
TO HIGH
PRESSURE
FITTING
Fig. 2 6 —Adding R efrigeration Oil Using Tool J-24095
at 5 0 0 0 ft. elevation,
REFRIGERANT
OIL
C A U T IO N : When removing the gauge lines from
the fittings, be sure to remove the adapters from the
system fittings rather than the gauge lines from the
adapter.
b. Turn on vacuum pum p, and open vacuum control
valve (slowly open high pressure side o f m anifold
gauge set to avoid forcing oil out o f refrigerant
system and pum p).
N O T E : When valve on tool J-24095 is opened, the
vacuum applied to the discharge side of the system
will suck oil into system fro m container. Therefore,
close observation o f oil level in the container is
necessary.
c. N ote level o f oil in container. O pen valve on oil
adding to ol un til oil level in container is reduced by
an am ount equal to th a t lost during discharge of
system + 1/2 ounce, th en close valve.
to add more oil than was lost.
d. D isconnect and cap too l J-24095 and reinstall low
pressure line from Charging S tation to the low
pressure fitting. Open low pressure valve (1).
Evacuation
A fter oil has been add ed to the system (as outlined above),
run pum p until 28-29 inches vacuum is o btained (See General
N ote under " Evacuating and Charging the S ystem " ). C ontinue
to run pum p for 10 m inutes after the system reaches 28-29
inches vacuum.
N O T E : If 28-29 inches cannot be obtained, close
Vacuum Control Valve (3) and shut o ff vacuum
pump. Open Refrigerant Control Valve (4) and
allow 1 /2 pound o f R-12 to enter system. Locate
and repair all leaks. Purge this 1 /2 pound and
re-evacuate fo r 10 minutes.
1. D uring the ten m inute evacuation period, prepare for
charging the system by filling the charging cylinder as
follows:
a. O pen valve on b o tto m o f charging cylinder allowing
refrigerant to enter cylinder.
N O T E : It will be necessary to close bleed valve
periodically to allow boiling to subside to check
level in the sight glass o f Charging Station cylinder.
b. Bleed cylinder valve on top (behind control panel)
as required to allow refrigerant to enter. When
refrigerant reaches desired level (see " System Capac­
ities"), close valve at b o tto m o f cylinder and be
certain bleed valve is closed securely.
2. C ontinue to evacuate for rem ainder o f 10 m inute period.
3. T urn hand shut-off valves at low and high pressure gauges
o f gauge set to full clockwise position w ith vacuum pum p
operating, th en stop pum p. Carefully check low pressure
gauge for approxim ately tw o m inutes to see that vacuum
rem ains constant. I f vacuum reduces, it indicates a leak in
the system or gauge connections; locate an d repair all
leaks.
Take care not
C H E V Y V A N S H O P M A N U A L