55
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 ca
n’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.
Finish charging by slowly opening the valve on the refrigerant manifold set to meter liquid
refrigerant into the low side of the system, with the compressor operating at maximum speed,
make sure to obtain the required sub-cooling and verify superheat shown in the table below. Use
a liquid charging adapter to prevent liquid refrigerant from entering the compressor. The unit
should be allowed to stabilize for 15 to 20 minutes to verify key measurements.
Function
R-410A Conditions
Liquid Line Pressure
290 to 390 PSIG (2000 to 2687 kPa)
Liquid Line Temperature
85 to 100 PSIG (586 to 690 kPa)
Suction Pressure
103 to 130 PSIG (710 kPa to 896 kPa)
Suction Saturated Temperature
33 to 45°F (0.56 to 7.22°C)
Subcooling
8 to 15°F (-13.33 to -9.44°C)
Differential Temperature - Depending on ambient
conditions, at compress
or’s maximum speed
Superheat
8 to 18°F (-13.33 to -7.78°C)
Differential Temperature
Measure the superheat at the compressor suction line at least 6 inches (152 mm) away from the
compressor. Compare suction pressure and temperature reading between the dap4 and the
manifold. If the difference between the manifold reading and dap4 reading is more than 5%,
check for the EEV wiring and any possible alarms on dap4, or EEV driver. Measure sub-cooling
at the liquid line.
When charging is complete, dd the correct amount of oil, if the line run exceeds longer than 66
feet (20 m). This procedure must be conducted with the system running at high load (compressor
at full speed). See
APPENDIX: Additional Oil Required (Oz)
proper amount of oil to add.
ALWAYS use clean original Danfoss POE oil 160SZ or equivalent from new cans.