Data Aire LCS Installation, Operation And Maintenance Manual page 22

control valve will regulate the fl ow of refrigerant to ensure nearly constant receiver pressure. The
condenser is partially fl ooded with liquid in cold weather. In warm weather the extra refrigerant is
stored in the receiver.
Flooded systems require more refrigerant than fan speed control systems. Connect the pressure
gauge manifold set to the high and low ports near the compressor. Connect the charging line to
the refrigerant tank and set it for liquid feed. Open the refrigerant tank valve and purge the line a
the manifold. Open the high side valve on the manifold only and allow the refrigerant to fl ow until
the system pressure equalizes. At this point the system will have 78 - 85% of the total refrigerant
charge. Start the (evaporator) blower. Start the compressor and check the operating pressures
and temperatures.
A quick and easy way to run the blower and compressor is using the manual switches on the unit
microprocessor. Switch the blower and compressor manual switches to the "ON" position. All
automatic control is disabled but safety switches will remain functional.
Before starting a compressor, the crankcase heaters should be energized for a minimum
of 12 hours to reduce the possibility of liquid slugging on start-up. Failure to energize
crankcase heaters could result in compressor damage.
Start the evaporator fan and verify the fan rotation. Start the compressor. Check the liquid line sight
glass to get a feel for the approximate charge. Bubbles in the sight glass are not unusual at this
point and can be caused by fl ashing from liquid pressure drop, low sub-cooling or low charge. It is
likely that more refrigerant will be required to complete the charging procedure.
If the receiver (head) pressure is below 230 PSI, block part of the condenser coil surface until the
pressure rises to 230 PSI or higher. During extremely cold weather all the condenser fans may have
to be de-energized to maintain 230 PSI.
Observe the sight glass on the receiver. Add refrigerant through the suction line until the level of
liquid in the receiver is approximately 1/3 from the bottom (the leveling ball in the receiver will start
to fl oat) of the sight glass. At this point the receiver is 80% full. Observing the receiver sight glass
becomes diffi cult when they are remote mounted near the condenser. The unit should be allowed
to stabilize for several minutes before meaningful measurements can be taken.
After the system is allowed to stabilize, the superheat at the compressor suction line (reading from at
least 6 inched from the compressor) should be 8 - 15°F. Unit with remote condensing units (DRCU)
the superheat should be 20 - 25°F at the compressor. The sub-cooling will be the same 8 - 10°F
as a standard. Remove any block that may have been used on the condenser coil. If the ambient
temperature while charging is below 60°F, some of the refrigerant will be backed up in the condenser
coil causing the liquid level in the receiver to drop, this is normal.
Note: Charging to a full liquid line sight glass should never be the sole means of
determining the correct refrigerant charge. Other parameters such as superheat, suction
pressure, head pressure, sub-cooling and ambient temperature are also important
parameters. A system charged to a clear sight glass is often overcharged.
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