Mitsubishi Electric CITY MULTI PUMY-P112VKM6 Service Manual page 72

6607 (A7): No ACK error
Diagnosis of failure
Continued from the previous page.
Is the correct kind of transmission line
used?
Is it operating different refrigerant
systems?
When operating in different refrigerant systems
(2 or more outdoor units), check if any of the
indoor unit stores non-existing address informa-
tion.
Is the address information correct?
Check the wiring.
Is the wiring on the circuit board
connected properly?
Replace the controller board which the displayed
address/attribute belongs to.
Does it operate normally?
OCH790 _72
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
Apply the correct kind of transmission line, then
perform the procedure 1.
When operating in a single refrigerant system
(single indoor unit), the controller of the dis-
played address/attribute is defective.
Delete the unnecessary address using a manual
setting function on the remote controller
(Only for the system to which the Fresh Master/
Lossnay is connected or the system in which a
group setting involving different refrigerant
systems is made).
Connect the wiring properly.
Defective outdoor multi controller circuit board
(repeater circuit) on the outdoor unit is suspect-
ed.
Replace the outdoor multi controller circuit board
one by one, then check for normal operation.
Complete.
Chart 4 of 4