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7. Troubleshooting
Problem
Unit does not power up,
power LED is OFF
Fault LED and buzzer ON
Fault LED ON and buzzer
OFF
Possible Cause
No power from fused spur.
Faulty power supply.
Blown power supply fuse.
Fault code read from indoor unit
which is not 8000 (8000 = OK).
High temp alarm has activated.
Incorrect number of indoor units
configured.
Invalid addressing of
MelcoBEMS MINI (A1M) units.
MelcoBEMS MINI (A1M) units
not powered up.
RS-485 wiring issue.
MelcoBEMS MINI (A1M) units
have Incorrect RS-485 comms
settings.
Interference on RS-485 cable.
A fault exists and the Mute
button has been pressed
Solution
Check fused spur
Check 230V mains voltage into power supply and
24VDV output.
Check fuse and replace if needed
Check indoor units for problems.
Check for indoor unit faults or other possible causes
of a high inlet temperature.
Check the number of units has been configured
correctly.
Check every MelcoBEMS MINI (A1M) unit has a
unique Modbus address (Slave ID), starting from
address 1.
Check the two LEDs on all connected MelcoBEMS
MINI units are either ON or flashing.
RS-485 wiring issue. Check all 'A', 'B' and 'GND'
connections are daisy chained together.
Check the MelcoBEMS MINI (A1M) comms settings
are set to 9600 baud, no parity.
Check shielded RS-485 cable has been used to
reduce possibility of electrical noise/interference.
Refer to the 'Fault LED and buzzer ON' problem for
information on the possible causes of the fault.
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