III-86
1. Purging Air From Gauge Set Hoses
Environmental regulations require that all service hoses have a shutoff valve
within 12 inches of the service end. These valves are required to ensure only a
minimal amount of refrigerant is lost to the atmosphere. R-12 gauge set hoses
have a valve near the end of all three hoses. R-134a gauge sets have a combina-
tion quick disconnect and shutoff valve on the high and low sides. The utility
(center) hose also requires a valve.
The initial purging is best accomplished when connected to recovery or re
-
cycle equipment. Figure 8-3 illustrates the gauge set connections for purging and
refrigeration recovery.
Note: The manifold gauges read system pressure when the hand valves
are closed if the hose end valves, and the stem type service valves
(if included) are open.
2. Adding Refrigerant to the System
Now that the gauges are connected, you may need to add some refrigerant to the
AC system before you can do an effective performance inspection. However, if
leaks are obvious they should be repaired prior to adding refrigerant.
Note: Loss of some refrigerant is not unusual over an extended period
of time. Adding refrigerant is a typical procedure when the AC
system is maintained on a regular basis.
When adding refrigerant to the system, connect the center hose from the mani-
fold gauge set to the refrigerant dispensing valve on the container. Figure 8-4
illustrates this connection.
Manifold Gauge Set Installation
Figure 8-3
The purging setup for
manifold gauge set and
compressor service valves
are shown here.
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