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