Chevrolet 10 Series 1967, Service Manual

Page: 44 / 605

HEATER AND AIR CONDITIONING 1A-16
FIVE A M P
TIME D ELAY
FU SE
C O R D TO P U M P PU M P D IS C H A R G E
110 A C S O U R C E INLET OUTLET
Fig . 26 - Vacuum Pump
CAUTION: Do not breathe the fumes that are
produced by the burning of R-12 gas in the de-
tector flame, since such fumes can be toxic in
large concentrations of R-12.
4. Watch for color changes. The color of the flame
which passes through the reaction plate will change
to yellow when sampling hose draws in very small
leaks of R-12. Large leaks will be indicated by a
change in color to a vivid purplish-blue. When the
sampling hose passes the leak, the flame will clear
to an almost colorless pale-blue again. If the flame
remains yellow when unit is removed from leak,
insufficient air is being drawn in or the reaction
plate is dirty.
Fig . 27 - Refrigerant-12 Disposable Cans and V alves
NOTE: A refrigerant leak in the high pressure
side of the system may be more easily detected
when, if possible, the system is in operation. A
leak on the low pressure side may be most
easily detected after the engine has been shut
off for several minutes to allow system pres­
sures to equalize. This particularly applies to
the front seal.
VACUUM PUMP
A vacuum pump should be used for evacuating air and
moisture from the air conditioning system.
Vacuum pump, Tool J-5428, (fig. 26) is available for
this purpose. It is used as a component part of the
Charging Station J-8393, described previously. The fol­
lowing precautions should be observed relative to the
operation and maintenance of this pump.
• Make sure dust cap on discharge outlet of vacuum
pump is removed before operating.
• Keep all openings capped when not in use to avoid
moisture being drawn into the system.
• Oil should be changed after every 250 hours of nor­
mal operation.
To change oil, simply unscrew hex nut located on back
side of pump, tilt backward and drain out oil (fig. 26).
Recharge with
8
ounces of vacuum pump oil Frigidaire
150 or equivalent (fig. 26). If you desire to flush out the
pump, use this same type clean oil. Do not use solvent.
NOTE:
Improper lubrication will shorten the
life of pump.
• If this pump is subjected to extreme or prolonged
cold, allow it to remain indoors until oil has reached
approximate room temperature. Failure to warm
oil will result in a blown fuse.
• A five ampere time delay cartridge fuse has been
installed in the common line to protect the windings
of the compressor. The fuse will blow if an ex­
cessive load is placed on the pump. In the event the
fuse is blown, replace with a five ampere time delay
fuse - do not use a substitute fuse as it will result in
damage to the starting windings.
• If the pump is being utilized to evacuate a bumt-out
CHEVROLET TRUCK SERVICE MANUAL