1-73
TROUBLESHOOTING
Yes
Yes
Faulty
Faulty
Check the inverter
circuit board. *2)
Turn off power, disconnect
U, V, W from compressor
terminals and restart.
Does the protecting function
activate? *3)
Check the transistor module
(5 to 20HP) or the ISPM (24
and 30HP). *1)
Good
Good
No
Is the heat exchanger of
outdoor unit clogged?
No
Check the compressor.
(If there is a short-circuit
between phase lines,
replace the compressor.)
Replace the transistor
module and inverter circuit
board.
Replace the transistor
module.
Replace the inverter
circuit board (5 to 20HP)
or ISPM (24 and 30HP).
Remove clogging.
Replace ISPM.
5 to 20HP
24 and 30HP
Yes
Is the silicon grease coated all over
between the transistor module and
the radiated fin? (5 to 20HP)
Is the silicon grease coated all over
between the ISPM and the radiated fin?
Is the fixed screw on ISPM loose?
(24 and 30HP)
No
Coat the silicon grease to all
the touched face between
the transistor module and the
radiated fin fully (5 to 20HP).
Coat the silicon grease to all
the touched face between
the ISPM and the radiated fin
fully. Fix the screw correctly
(24 and 30HP). *4)
“RUN” light flickers and “ALARM” is indicated on the remote control switch.
The unit No., alarm code and the unit code is alternately indicated on the set temperature section,
and the unit No. and alarm code are indicated on the display of the outdoor unit PCB.
Transistor module (5 to 20HP) or ISPM (24 and 30HP) have detecting function of abnormality.
This alarm is indicated when the transistor module detect the abnormality 3 times in 30 minutes
including 3. Retry operation is performed up to the occurrence of 2 times. (In Case of 5 to 20HP)
In case that the abnormality of alarm code 51, 52, 53 or 54 occurs three times within 30 seconds, the
alarm code of abnormality occurred for the third time is indicated. Retry operation is performed up to
second time of abnormality occurrence. (In Case of 24 and 30HP)
Conditions:
Abnormal Current to the Transistor Module (5 to 20HP) or ISPM (24 and 30HP) such as
Short Circuited or Grounded
or
Abnormal Temperature of the Transistor Module (5 to 20HP) or ISPM (24 and 30HP)
or
Control Voltage Decrease
1*): Regarding replacing or checking method for the transistor module (5 to 20HP) and the inveter components (24
and 30HP), refer to pages 1-112 and 1-114.
2*): Before the checking of inverter components, refer to page 1-111 regarding electrical discharge.
3*): Turn ON the No.1 switch of the dip switch DSW1 on PCB3/ISPM when restarting with disconnecting
theterminals of the compressor. After troubleshooting, turn OFF the No.1 switch of the dip switch DSW1 on
PCB3/ISPM (5 to 20HP/24 and 30HP).
4*): Use the silicon grease provided as accessory (Service Parts No.: P22760).
Alarm
Code
Protection Activation of Transistor Module (5 to 20HP)
or ISPM (24 and 30HP)
