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158 RTAC-SVX01F-EN
Maintenance Procedures
NOTE: Units with a design sequence of A0 did not have enough capacity in the
condenser to hold the entire charge. Table 37 lists the amount of charge that would
flood the oil separator if the charge was isolated in the high side. For this reason,
when getting the unit back to running condition, care must be taken to drive the refrig-
erant out of the oil separator using the oil separator heaters.
Returning unit to running condition:
1. Open all valves.
2. Manually open EXV for 15 minutes to allow refrigerant to drain to evaporator by
gravity (ensure water is flowing in the evaporator prior to opening the EXV).
3. Let unit sit with heaters on to drive refrigerant out of oil and warm up compressor
bearings. Depending upon ambient conditions, this may take up to 24
hours.Ensure the UCM is powered so the pump may be energized if it detects a
freeze condition.
4. Once the oil level has returned to normal, the unit can be put back into operation.
Low side charge isolation procedure:
After normal shut down under some conditions most of the charge resides in the
evaporator. Running cold water through the evaporator may also drive much of the
refrigerant to the evaporator.
1. Make sure circuit is off.
2. Close suction line isolation valve.
3. Close oil return line service valve.
4. Close liquid line service valve.
5. Manually open EXV.
6. Use a liquid pump or vacuum pump to move refrigerant from the condenser to
evaporator. The liquid pump will only be effective if there is a lot of charge in the
condenser. It may be connected to the condenser drain port on the liquid line
isolation valve.
NOTE: If a pump is to be used, connect it before closing this valve. This port is only
isolated when the valve is back seated.
If a vacuum pump is used, then connect it to the discharge line service valve near the
oil separator.
A vacuum pump will be required for part of the procedure.
Table 37 Charge Holding Capabilities on High Side
Nominal Circuit
Capacity
Nominal Circuit
Charge
lb
Condenser Charge
Holding Capacity
@ 60% full
90
o
ambient
lb
Charge in Oil
Separator
lb
% Oil Separator
Level
70 165 118.1 46.9 97.7
85 175 134.3 40.7 86.0
100 215 163.7 51.3 56.0
1 2 0 2 2 5 1 8 7. 9 3 7. 1 4 1 . 2
170 365 203.4 161.6 100.0%
200 415 282.0 133 86.1 %
240 460 325.6 134.4 86.9 %
Circuit varies slightly with efficiency and unit configuration