Mitsubishi Electric PUMY-P200YKM2 Technical & Service Manual page 75

Check code
6603
(A3)
Abnormal points and detection methods
An abnormality when no transmission status caused by transmitting
data collision continues for 8 to 10 minutes.
An abnormality when data cannot be output on the transmission line
consecutively because of noise etc. for 8 to 10 minutes.
●Diagnosis of defects
Make sure to turn the power OFF before connecting/disconnecting any connectors, or replacing boards.
Check whether the transmission line to
the indoor unit, Fresh Master, Lossnay
or remote controller is miswired to the
terminal block (TB7) on outdoor unit or not.
Is the transmission line miswired?
Check whether the transmission line with
the other refrigerant system of the indoor
unit, Fresh Master or Lossnay is miswired
to the terminal block (TB3) on outdoor unit
or not.
Is the transmission line miswired?
Turn the power back ON.
Does it operate normally?
OCH675D
Transmission bus BUSY error
Diagnosis
(miswired)
(wired correctly)
No
(miswired)
(wired correctly)
No
Yes
Causes and checkpoints
The transmission processor is unable to transmit due
to a short-cycle voltage such as noise is mixed on
the transmission line.
The transmission processor is unable to transmit due
to an increase of transmission data amount caused
by a miswiring of the terminal block (transmission
line) (TB3) and the terminal block (centralized control
line) (TB7) on the outdoor unit.
The share on transmission line becomes high due
to a mixed transmission caused by a malfunction
of repeater on the outdoor unit, which is a function
to connect/disconnect transmission from/to control
system and centralized control system.
Correct the wiring, then turn the power
Yes
back ON.
Correct the wiring, then turn the power
Yes
back ON.
Replace the indoor/outdoor controller
No
board.
There is no abnormality on the AC unit.
It might be caused by an external noise, so check
the transmission line to remove the factor(s).
75
Remedy