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9
Troubleshooting
On the next pages you will find a list of the most common causes that may cause the package unit to fail or
malfunction. These causes are broken down according to easily identifiable symptoms.
You should be extremely careful when attempting to implement any of the possible
remedies suggested: overconfidence can result in injuries, even serious ones, to
inexpert individuals. Therefore, once the cause has been identified, you are advised to
contact the manufacturer or a qualified technician for help.
FAULT
The unit does not start
The compressor is noisy
Presence of abnormally high
pressure
Low condensation pressure
Low evaporation pressure
The compressor does not
start
@DNOVA THN_R410A-IOM-1506-E
POSSIBLE CAUSES
No power supply
The electronic card is cut off from
the power supply
Alarms have been triggered
The phase sequence is wrong
The compressor is rotating in the
wrong direction
Insufficient flow of air to the
condenser
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
Unit overcharged, as revealed by
an Sub-cooling of more than 8 °C
Thermostatic valve and/or filter
obstructed. These symptoms may
also occur in the presence of an
abnormally low pressure
Transducer fault
Malfunctioning of thermostatic
valve
Filter dryer clogged
Low condensation T
Low level of refrigerant
The internal thermal protection
device has tripped
The circuit breakers or line fuses
have been tripped by a short circuit
One of the high or low pressure
switches has tripped
The phases have been inverted in
the distribution compartment
CORRECTIVE ACTIONS
Check that power is being supplied both to the primary
and auxiliary circuits
Check the fuses
Check whether any alarms are signalled on the
microprocessor control panel, eliminate the causes
and restart the unit
Invert two phases in the primary power line after
disconnecting them upstream from the unit
Check the phase sequence relay. Invert the phases on
the terminal board after disconnecting the unit and
contact the manufacturer
Check for the presence of obstructions in the
condenser section ventilation circuit
Check whether the condenser coil surface is
obstructed
Check the condensation control device (optional)
Drain and pressurise the circuit and check for leaks.
Evacuate slowly (for more than 3 hours) until reaching
a pressure of 0.1 Pa and then recharge in the liquid
phase
Drain the circuit
Check the temperatures upstream and downstream
from the valve and filter and replace them if necessary
Check the efficiency of the condensation control
device (optional)
Warming the bulb with your hand, check whether the
valve opens and adjust it if necessary. If it does not
respond, replace it
Pressure drops upstream and downstream from the
filter should not exceed 2°C. If they do, replace the
filter
Check the efficiency of the condensation control
device (where present)
Check the refrigerant level by measuring the degree of
Sub-cooling; if it is below 2°C replenish the charge
In the case of compressors equipped with a protection
module, check the thermal contact. Identify the causes
after restarting
Pinpoint the cause by measuring the resistance of the
individual windings and the insulation from the casing
before restoring power
Check on the microprocessor, eliminate the causes
Check the phase sequence relay
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