Installation, Operation and Maintenance Manual
Page
30
of
100
signal to 0V. Enabling any other manual mode switch will likewise disable all control outputs from the dap4 panel
resulting in full manual mode operation and setting the plug fans to 0V. To test the plug fan modules in manual
mode, turn on blower and fan speed switch on manual over-ride modules. This will enable the fan control signal at
approximately 90%. The fans will spin at near full speed.
WARNING
Before starting a compressor, the crankcase heater should be
energized for a minimum of 12 hours to reduce the possibility of liquid slugging
on start-up. Failure to energize the crankcase heater could result in compressor
damage. If the system is charged from a vacuum, the preheating of the
compressor is not necessary.
Start the evaporator fan and verify the fan rotation. From a vacuum, add liquid refrigerant to the high side of the
system until the pressures equalize. 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 flashing from
liquid pressure drop, low sub-cooling or low charge. It is likely more refrigerant will be required to complete the
charging procedure.
If the receiver (head) pressure is below 322 PSIG with R-410A, block part of the condenser coil surface until the
pressure rises to 322 PSIG R-410A or higher. If the receiver (head) pressure is below 322 PSIG with R-410A, block
part of the condenser coil surface until the pressure rises to 322 PSIG for R-410A or higher. During extremely cold
weather all the condenser fan must be de-energized to maintain head pressure.
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 of the sight-glass (the leveling ball in the receiver will start to float).
At this point the charging is correct. Observing the receiver sight-glass becomes difficult when they are remotely
mounted near the condenser. The unit should be allowed to stabilize for several minutes before meaningful
measurements can be taken.
After the system is stabilized, the superheat at the compressor suction line (reading from at least 6 inches from the
compressor) should be 8°F to 15°F. Remove any blocks that may have been used on the condenser coil. If the
ambient temperature while charging is below 70°F, some of the refrigerant will be backed up into the condenser
coil causing the liquid level in the receiver to drop (this is normal).
NOTICE
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. A system charged to a clear sight glass is
often overcharged.
For all gPods, both cooling mode and reheat mode need to be checked. Fully charge the gPod in cooling mode only.
Once full charge is adequate in cooling mode, engage reheat mode
wi
th the controller reheat mode. The charge in
reheat mode may need to be adjusted but always check cooling mode again to verify operating pressures are
adequate.
WARNING
R-410A Refrigerant is used in gPod systems. Death or serious injury
may result if personnel fail to observe proper safety precautions. Great care
must be exercised to prevent contact of liquid refrigerant or refrigerant gas,
