HEATER AND AIR CONDITIONING 1A-14
The pump mount is such that the dealer may use his own vacuum pump. The gauges and manifold are in com mon use. Thus a current air conditioning dealer can use the equipment on hand and avoid duplication.
GAUGE SET The gauge set (fig. 22) is an integral part of the J-8393 Charging Station. It is used when purging, evacuating, charging or diagnosing trouble in the system. The gauge at the left is known as the low pressure gauge. The face is graduated into pounds of pressure and, in the opposite direction, in inches of vacuum. This is the gauge that should always be used in checking pressures on the low pressure side of the system. When all parts of the sys tem are functioning properly the refrigerant pressure on the low pressure side never falls below 0 pounds pres sure. However, several abnormal conditions can occur that will cause the low pressure to fall into a partial vac uum. Therefore, a low pressure gauge is required. The high pressure gauge is used for checking pres sures on the high pressure side of the system. The hand shutoff valves on the gauge manifold do not control the opening or closing off of pressure to the gauges. They merely close each opening to the center connector and to each other. During most diagnosing and service operations, the valves must be closed. Both valves will be open at the same time during purging, evacuating and charging operations. The charging station provides two flexible lines for connecting the gauge set to the system components.
FIVE A M P TIME D E L A Y FUSE
C O RD TO 110 AC SO U R C E
PUMP INLET
P U M P D IS C H A R G E OUTLET
V A C U U M PUMP A vacuum pump should be used for evacuating air and moisture from the air conditioning system. The vacuum pump (fig. 23) is a component part of 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.
1 L O W PRESSU RE CONTROL
Fig. 23— Vacuum Pu mp
H IG H PR ESSU R E CONTROL
3
4
VACUUM CONTROL
FREON CONTROL
• Oil should be changed after every 250 hours of normal operation. To change oil, simply unscrew hex nut located on back side of pump, tilt backward and drain out oil (fig. 23). Recharge with 8 ounces of vacuum pump oil, Frigidaire 150 or equivalent (fig. 23). If you desire to flush out the pump, use the same type clean oil. Do not use solvent. NOTE:
Improper lubrication will shorten pump
life.
Fig. 2 2 — Charging Station G auge Set
• 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.
10-30 CHEVROLET TRUCK SERVICE MANUAL
