Mitsubishi Electric MXZ-SM72TAM-U1 Service Manual page 69

6602 (A2): Transmission processor hardware error
Abnormal points and detection methods
The transmission line shows "1" although the transmission
processor transmitted "0".
Diagnosis of failure
A wiring work was performed while the
power was OFF.
Turn the power back ON.
Does it operate normally?
OCH800A_69
No
Yes
No
Yes
Causes and checkpoints
• A transmitting data collision occurred because of a
wiring work or polarity change has performed while the
power is ON on either of the indoor/outdoor unit, Fresh
Master or Lossnay.
• Malfunction of transmitting circuit on transmission pro-
cessor
• Noise interference on indoor/outdoor connectors
If the wiring work was performed while the power
was ON, turn the power OFF of indoor/outdoor
unit, Fresh Master or Lossnay simultaneously for
2 minutes or more, then turn the power back ON.
Replace the indoor/outdoor controller 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).