6-1
6. TROUBLESHOOTING
6.1 Refrigeration system and electrical system
If the unit does not work properly, refer to the following table to find causes of trouble and provide
appropriate measures.
State
Malfunction occurrence
Abnormal point Possible cause
A. Neither evaporator q No trouble with unit Power failure
fan, condenser fan nor
Equipment power supply: OFF
compressor ran. Disconnection of power plug
Poor contact of power plug
w Circuit breaker Circuit breaker: OFF
Solenoid valve coil burned out or short circuit
Contactor coil burned out or short circuit
Short circuit of wiring inside unit
e UNIT ON/OFF key OFF or malfunction
r Controller Wire breakage in the control circuit transformer
Fuse (10A) burned out
Open phase (R or T)
Shut down due to alarm generation
t Power transformer Wire breakage or open phase
B.
Evaporator fan rotates,
No trouble with unit ON/OFF control with frozen mode
but condenser fan and
(Inside temperature is lower than SP.)
compressor do not rotate.
C.
Condenser fan rotates,
Activation of electronic Overcurrent due to overload operation, etc.
but evaporator fan and
overcurrent protection
compressor do not rotate.
device, PT/CT board.
D. Compressor rotates, Fan motor, actuation of Fan locked by foreign material
but evaporator fan and
protection thermostat Not-closing of protection thermostat contact
condenser fan do not rotate.
point
E. Compressor buzzes, q Compressor Open phase
but it does not operate.
Lock
Low supply voltage
Motor coil burned out or short circuit
w Power transformer Power transformer malfunction
A. Unit starts but soon q High-pressure switch malfunction
stops
w Liquid solenoid valve: closed
Electronic expansion valve: closed
e Overcurrent due to overload operation, etc.
r
Activation of compressor
Overcurrent due to overload operation, etc.
thermal protector
B.
Evaporator fan rotates,
q No trouble with unit In ON-OFF control operation with frozen mode
but condenser fan and
compressor do not rotate.
C.
Condenser fan rotates,
q Activation of high- Refrigerant overcharge
but evaporator fan and
pressure switch Air entering in the refrigerant system
compressor do not (Air cooled
Insufficient air flow rate in the air cooled condenser
rotate
.
condenser type) Condenser finned coil blocked
Air passage blocked by foreign material
Broken blade of condenser fan
Condenser fan motor rotation failure
Activation of condenser fan motor thermal protector
1 unit does not operate2 Unit operates but soon stops
Activation of HPS within 30
seconds after compressor
starting
Activation of electronic
overcurrent protection
devices, PT/CT board
Abnormal low pressure
drop within 2 seconds
after compressor starting
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