GMC 1976 ZEO 6083 Maintenance Manual page 754

NOTE :
Gauge readings at higher altitudes will be
less than the sea level rating of 29-1/2 inches Hg .
Warming the unit in high altitudes and/or low
temperatures will make the air or water in the
system vaporize more readily. To warm, place
the unit directly in front of a shop heater, or
paint drying lights . Do not use any direct flame
for warming.
The pump can be tested by connecting it to a
clear soft-drink bottle, 3/4 full of water. If the water
in the bottle begins to bubble, the pump is function-
ing.
2. If an automotive pump is used, "break" the
evacuation vacuum twice with a charge of R-22 to
about 100 psi and repeat the evacuation to be sure to
get all air and moisture out. This is not necessary
with charging station J-24410.
3. Leak test the system . Stop the vacuum pump
and watch the gauge. If the vacuum holds, the sys-
tem is tight and can be charged.
4. Connect the dial-a-charge or charging station
in place of the pump . Purge the line briefly at the
gauge port, then admit the specified charge .
CAUTION :
Be sure to measure the charge
accurately . The specification is critical with
the capillary tube metering system . Each air
conditioning unit has an identification tag
that specifies the exact charge for that unit.
5 . If necessary during charging, start the com-
pressor and run it until the charge enters . When the
charge is in, shut off the refrigerant .
CLOSING THE REFRIGERATION SYSTEM
1. Pinch off the process tube next to the tap valve.
Remove the tap valve.
2. Cut off the tube and braze the end to hermeti-
cally seal the system before you remove the pinching
SPECIFICATIONS
ROOF MOUNTED AIR CONDITIONER 24E- 1 5
Figure 18-Charging
SPECIAL TOOLS
J-24673 Cycle Tester
J-21008 Self-Powered Test Light
J-6084 Leak Detector, Flame Type
J-23400-01 Leak Detector, Electronic
J-24410 Charging Station
COMPRESSOR MOTOR RESISTANCE VALUES
Station J-24410
tool .
The pinch off
tool acts as a heat sink during the
brazing, preventing decomposition of the refrigerant .
Model
54615
Windings Resistance
in Ohms +10%
Start Run
4 .83 .378