JOHNSON CONTROLS
98
FORM 150.72-ICOM7
ISSUE DATE: 10/22/2020
SECTION 6 – COMMISSIONING
6. Open the valve on the drum and reverse the drum,
so only liquid is charged into the system.
7. Monitor the reading of the scale and shut o the
valve when the scale reaches W.
8. Close the angle valve and switch the charging
pipe from angle valve to Schrader valve between
the evaporator and EEV/TXV.
9. Purge the air from the charging pipe.
10. Open the valve on the drum to charge the remain-
ing 10% of the system charge into the low side.
However, sometimes the system can run without
enough refrigerant in it. If you have no idea how much
refrigerant is inside of the system, then follow the steps
below.
1. Connect the charging hose between the refrigerant
tank and the angle valve at the inlet of evaporator.
Exclude the air inside of hose.
2. Put the refrigerant tank on a scale and read the ini-
tial weight. Leave the tank on scale until process
is complete.
3. Get as many compressors running as the system
permits.
4. Open the angle valve 1.5 turns.
5. Open the valve on the tank.
Quickly shut down the angle valve or
the tank valve immediately if all of com-
pressors stop suddenly in the process of
charging.
6. Monitor the suction superheat (SH) and liquid
subcooling (SC). If SH is around 10R and SC>6R,
close the angle valve. Wait at least 15 min;
7. If SC<10R or SH>10R always, continue to charge
the system. Open the angle valve 1.5 turns. Close
it after one pound is added. Wait another 15 min.
Repeat this step until both SC and SH are around
10R with all of the fans and compressors running;
8. Close the angle valve and tank valve. Disconnect
the hose.
Service and Oil Line Valves
Open each compressor suction, economizer, and dis-
charge service valve. If valves are of the back-seat
type, open them fully (counterclockwise) then close
one turn of the stem to ensure operating pressure is fed
to pressure transducers. Open the liquid line service
valve and oil return line ball valve fully in each system.
Compressor Oil
To add oil to a circuit – connect a Johnson Controls
hand oil pump (Part No. 470-10654-000) to the 1/4 in.
oil charging connection on the compressors with a
length of clean hose or copper line, but do not tighten
the flare nut. Using clean oil of the correct type (“V”
oil), pump oil until all air has been purged from the
hose then tighten the nut. Stroke the oil pump to add oil
to the oil system. Approximately 1.8 to 2.3 gal is pres-
ent in the each refrigerant system. Oil levels in the oil
equalizing line sight glass should be between the bot-
tom and the middle of the sight glass with the system
OFF. High oil levels may cause excessive oil carryover
in the system. High oil concentration in the system may
cause nuisance trips resulting from incorrect readings
on the level sensor and temperature sensors. Tempera-
ture sensor errors may result in poor liquid control and
resultant liquid overfeed and subsequent damage to the
compressor. While running, a visible sign of oil splash-
ing in the sight glass is normal.
Fans
Check that all fans are free to rotate and are not dam-
aged. Ensure blades are at the same height when ro-
tated. Ensure fan guards are securely fixed.
Isolation / Protection
Verify all sources of electrical supply to the unit are
taken from a single point of isolation. Check that the
maximum recommended fuse sizes given in SECTION
5 – TECHNICAL DATA has not been exceeded.
Control Panel
Check the panel to see that it is free of foreign materi-
als (wire, metal chips, etc.) and clean out if required.
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