Data Aire gForce Ultra - Charging the Variable Speed Compressor

gForce Ultra IOM
59
6. Add the calculated amount of refrigerant. At this point, there will be approximately 70 to
80% of the total charge in the system. It is likely that more refrigerant will be required to
complete the charging procedure during compressor operations.
7. Close the valve on the refrigerant manifold gauge set.
WARNING: If the system is charged from a vacuum, the preheating of the
compressor is not necessary. But if starting a compressor that has not
been charged from a vacuum, the crankcase heater must 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.
Charging the Variable Speed Compressor
The variable speed compressor requires a little more care while charging. All unit safeties must be
active while charging the compressor. Start the system by changing the Temperature Setpoint under
Menu B – Setpoints on the dap4 controller. The unit must be started in the normal operating mode
based on a call for cooling required by the dap4 controller once an initial charge has been added to the
circuit. Before starting the system, make sure pressure gauges and suction line temperature sensor
are hooked up and refrigerant readings are aligned with EEV reading. For dual circuit units, remove the
fixed speed compressor’s fuses to prevent it from starting.
If the unit is in OFFbyKEY position, hold the “Esc” key for 5 seconds to start the system via the dap4
controller. The return air temperature needs to be higher than temperature setpoint plus deadband for
the compressor to start.
Example: Existing return air temperature is 75F (24C) , set the dap4 Temperature Setpoint to 65F
(18C). The variable speed compressor will start and run at a full speed.
When the compressor starts, monitor closely the suction pressure, head pressure, compressor VFD
display and the EEV. Watch for any alarms that you might see. During startup, you might see some
alarms such as:
• C1 Low Pressure: If suction pressure is below the pressure cutout, make sure to add more
refrigerant per recommended charge calculation shown above.
• Compressor VFD Alarm: This alarm shows up when the compressor is called upon for
cooling requirement, but either the VFD has stopped the compressor, or the compressor is
experiencing a Low- or High-pressure alarm.
• Out of Envelope Alarm: This alarm appears when the running pressures are out of normal
operating range.
• Pump-Down Failure: This alarm appears when the system can’t pump down; refrigerant in
the evaporator can’t come down to 90 PSI (621 kPa), normally due to open/leaking liquid line
solenoid valve, electronic expansion valve, oil line solenoid valve, and/or no oil in the oil
separator.