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17 TROUBLESHOOTING
Symptom Cooling Heating
Who can take
corrective action U
= User
S = specialised
personnel
Probable cause Possible remedy
A The unit does
not start
Probe faulty service
Check and replace if necessary.
Lack of consent of the high or low
pressure
See points D-E
Defective compressor See point B.
B The compressor
does not start
Compressor burnt or seized Replace the compressor.
x x s
Compressor contactor de-
energized
Check the voltage across the coil of the
compressor contactor and the continuity of
the coil.
x x s
Power circuit open
Investigate the cause of the protection, and
check if there are any short circuits in the
wiring
or in the windings of the motors of pump,
compressor and transformer
x x s
Motor thermal protection open
The compressor has operated in critical
condition or there is a lack of charge in the
circuit: Make sure that working conditions
are within the limits of operation. Loss of
coolant: see section G.
C The
compressor starts
up and stops
repeatedly
Intervention of the minimum
x x s
Compressor contactor defective Check and replace if necessary.
x x u
Calibration values of the set- point
or differential
Modify them as reported in the in the tables.
Lack of coolant See point G
D The compressor
does not start
because the
maximum
pressure switch
has tripped
Pressure switch out of order Check and replace.
x x s
Overcharge of refrigerant Download the excess refrigerant
x s
Water pump circulation blocked Unblock the pump.
x x
Water circulation pump and
defective
Check and replace if necessary.
x x s
Presence of non-condensable
gases in the refrigerant circuit
Prime the circuit after it has been
downloaded and put under vacuum.
Refrigerant filter clogged Check and replace.
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