Mitsubishi Electric CITY MULTI PUMY-P112VKM6 Service Manual page 73

6608 (A8): No response frame error
Abnormal points and detection methods
Although the sending side controller received ACK that
notifies the reception of signal, no response command is
transmitted from the receiving side.
The sending side detects the abnormality when that occurs
6 times in succession at 30 second intervals.
Diagnosis of failure
Turn the power OFF of indoor/outdoor unit,
Fresh Master, Lossnay and remote controller
simultaneously for 2 minutes or more, then turn
the power back ON.
Does it operate normally?
Check the transmission line for disconnection
and looseness (on the terminal board and
connector).
The transmission line is connected
properly.
Check the transmission line whether it exceeds
the limits or not.
It exceeds the limits.
Check whether the correct kind of transmission
line is used or not.
Is correct kind of transmission line
used?
OCH790 _73
No
Yes
No
Yes
Yes
No
No
Yes
Causes and checkpoints
• Continuous failure of transmission due to noise, etc.
• Decline of transmission voltage/signal because the
transmission line exceeds the following limits.
- Indoor/outdoor transmission line maximum distance:
200 m [656 ft]
- On remote controller line: 12 m [39 ft]
• Decline of transmission voltage/signal due to un-
matched transmission line types
- Types for shield line: CVVS, CPEVS, or MVVS
- Line diameter: 1.25 mm
• Accidental malfunction of error source controller
Replace the controller board
(Defect of the controller which the displayed
address/attribute belong to).
Connect the transmission line properly.
Correct it within the limits.
Replace it with the correct kind of transmission
line.
There is no abnormality on the AC unit.
Check the transmission line for transmission
wave and noise.
2
[AWG 16] or more