No Response Frame Error; 6608 - Mitsubishi Electric PUMY-P250YBM Technical & Service Manual

Check code

6608

(A8)
Abnormal points and detection methods
If receiving no response command while already received ACK.
The sending side searches the error in 30 seconds interval for 6 times
continuously.
●Diagnosis of defects
Make sure to turn the power OFF before connecting/disconnecting any connectors, or replacing boards.
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 tolerance or not.
It is not exceeding the tolerance.
Check whether the correct kind of
transmission line is used or not.
Is correct kind of transmission line
used?
OCH760

No response frame error

Diagnosis
Yes
Yes
Yes
Yes
Causes and checkpoints
Continuous failure of transmission due to noise, etc
Decline of transmission voltage/signal caused by
tolerance over on transmission line
·At the furthest end: 200 m
·On remote controller line: (12 m)
Decline of transmission voltage/signal due to
unmatched transmission line types
·Types for shield line: CVVS, CPEVS or MVVS
·Line diameter: 1.25 E or more
Accidental malfunction of error source controller
Replace the controller board
(Defect of the controller which the
No
displayed address/attribute belong to).
No Connect the transmission line properly.
Correct it within the tolerance.
No
Replace it with the correct kind of
No
transmission line.
There is no abnormality on the AC unit.
Check the transmission line for
transmission wave and noise.
82
Remedy