PKG-SVX029A-EN
47
NOTICE
Motor Winding Damage!
Failure to follow instructions below could result in
compressor motor winding damage.
Do not use a megohm meter or apply voltage
greater than 50 VDC to a compressor motor
winding while it is under a deep vacuum.
• Open valves B and C. Evacuate system to a pressure
of 300 microns or less. As vacuum is being pulled on
system, it may appear that no further vacuum is being
obtained, yet pressure is high. It is recommended
during evacuation process to break vacuum to facilitate
evacuation.
• To break the vacuum, shut valves A, B, and C and
connect a refrigerant cylinder to charging port on
manifold. Purge air from hose. Raise standing vacuum
pressure in system to zero (0 psig) gauge pressure.
Repeat process two or three times during evacuation.
Note: It is unlawful to release refrigerant into the
atmosphere. When service procedures require
working with refrigerants, the service technician
must comply with all Federal, State, and local
laws.
Standing Vacuum Test
Once 300 microns or less is obtained, close valve A and
leave valves B and C open to allow the vacuum gauge to
read the actual system pressure. Let system equalize for
approximately 15 minutes. This is referred to as a standing
vacuum test where time versus pressure rise. Maximum
allowable rise over a 15 minute period is 200 microns. If
pressure rise is greater than 200 microns but levels off to a
constant value, excessive moisture is present. If pressure
steadily continues to rise, a leak is indicated. Figure 23, p.
47 illustrates three possible results of standing vacuum
test.
If a leak is encountered, repair the system and repeat the
evacuation process until the recommended vacuum is
obtained. Once the system has been evacuated, break the
vacuum with refrigerant and complete the remaining Pre-
Start procedures before starting the unit.
Figure 22. Typical vacuum pump hookup
Figure 23. Evacuation time vs. pressure rise
200
400
600
800
1000
1200
1400
1600
-10 0 10 20 30 40 50 60 70 80 90
Pressure in Microns
Time in Minutes
Continously increasing pressure
indicates the presence of leaks,
moisture, or both.
Initial evacuation pressure.
State of equilibrium indicates the
true amount of moisture left in
the system. It indicates that no
leaks are present and the system
is properly evacuated.
State of equilibrium indicates the
true amount of moisture left in
the system. It indicates that no
leaks, but requires further evacuation.
Maintenance
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