EWWQ090G ÷ EWWQ720L - R410a - Water-cooled scroll chillers
EWLQ090G ÷ EWLQ720L - R410a - Condenser less
EWHQ100G ÷ EWHQ400G - R410a - Heat pump scroll chillers
Water cooled scroll chillers & heat pump
Operation
Manual
EWWQ - EWLQ - EWHQ
Water cooled scroll chiller &heat
pump
D-EOMWC01203-15EN
Operation Manual
53
Check for correct plug-in of the
electrical connectors.
Check for correct sensors wiring also
according with electrical scheme.
6.1.6 Circuit Rapid Stop Alarms
6.1.6.1 Failed Pumpdown
This alarm is generated to indicate
that the circuit hadn’t been able to remove all the refrigerant
from the evaporator.
Symptom
Cause
Solution
Circuit status is Off.
Led on the button 2 of External HMI is
blinking
String in the alarm list:
+Cx FailedPumpdownAlm
String in the alarm log:
Cx FailedPumpdownAlm
String in the alarm snapshot:
Cx FailedPumpdown Alm
EEXV is not closing completely,
therefore there’s “short-circuit”
between high pressure side with low
pressure side of the circuit.
Check for proper operation and full
closing position of EEXV. Sight glass
should not show refrigerant flow after
the valve is closed.
Check that the C-LED on the EXV
driver is solid green. If both LEDs on
the EXV driver are blinking alternately
the valve motor is not properly
connected.
Evaporating pressure sensor is not
working properly.
Check for proper operation of
evaporating pressure sensor.
Compressor on circuit is internally
damaged with a mechanical problems
for example on internal check-valve,
or on internal spirals or vanes.
Check compressors on circuits.
6.1.6.2 Low Pressure alarm
This alarm is generated if the evaporating pressure drops below the Low Pressure Unload and the
control is not able to compensate this condition.
Symptom
Cause
Solution
Circuit status is Off.
The compressor does not load
anymore or even unload, circuit is
stopped immediately.
Bell icon is moving on controller’s
display.
Led on the button 2 of External HMI is
blinking
String in the alarm list:
+Cx Off EvapPressLo
String in the alarm log:
Cx Off EvapPressLo
String in the alarm snapshot:
Cx Off EvapPress Lo
Refrigerant charge is low.
Check sight glass on liquid line to see
if there is flash gas.
Measure sub-cooling to see if the
refrigerant charge is correct.
Protection limit not set to fit customer
application.
Check the evaporator approach and
the corresponding water temperature
to evaluate the low pressure hold
limit.
High Evaporator Approach.
Clean the evaporator
Check the quality of the fluid that
flows into heat exchanger.
Check the glycol percentage and type
(ethilenic or propilenic)
Water flow into water heat exchanger
is too low.
Increase the water flow.
Evaporating pressure transducer is
not working properly.
Check the sensor for proper operation
and calibrate the readings with a
gauge.