LCA
RG66000986 – Rev.00
26
FAULT
Possible causes
Corrective actions
The unit does not start
No power supply
Check that power is being supplied
both to the primary and auxiliary
circuits.
The electronic card is cut off from
the power supply
Check the fuses
Alarms have been triggered
Check whether any alarms are
signalled on the microprocessor
control panel, eliminate the causes
and restart the unit.
The phase sequence is wrong
Invert two phases in the primary
power line after disconnecting
them upstream from the unit
The compressor is noisy
The compressor is rotating in the
wrong direction
Check the phase sequence relay.
Invert the phases on the terminal
board after disconnecting the unit
and contact the manufacturer.
Presence of abnormally high
pressure
Insufficient flow of air to the
condenser
Check whether all the fans are
turning properly
Check the air T at the condenser
inlet and make sure no back
suction occurs
Check whether the effective RMS
voltage to the fans is the
maximum. If necessary, check the
pressure transducers controlling
the revolution regulator, where
present [optional]
Check the cleanliness of the finned
coils
Presence of air in the refrigerant
circuit, as revealed by the
presence of bubbles in the flow
indicator also with undercooling
values exceeding 5 °C
Drain and pressurise the circuit
and check for leaks. Generate a
slow vacuum [longer than 3 hours]
until reaching a pressure of 15 Pa
and then recharge in the liquid
phase
Unit overcharged, as revealed by
an undercooling of more than 8 °C
Drain the circuit
Thermostatic valve and/or filter
obstructed. These symptoms may
also occur in the presence of an
abnormally low pressure.
Check the temperatures upstream
and downstream from the valve
and filter and replace them if
necessary.
Insufficient flow of water in the
case of heat pump operation
Check the water circuit for
pressure drops and/or whether the
pump is working properly [direction
of rotation]. Check the outgoing
water T and make sure it less than
or equal to 45°C