Mitsubishi Electric PUZ-HA24NHA1, Service Manual

Page: 40 / 128

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OCH750A
Continued to the next page.
Abnormal point and detection method Cause Judgment and action
A7
(6607)
NO ACK signal
1. Transmitting side controller detects
abnormal if a message was transmitted
but there is no reply (ACK) that a mes-
sage was received. Transmitting side
detects abnormality every 30 seconds, 6
times continuously.
Note: The address and attribute displayed
at remote controller is indicate the
controller that did not reply (ACK).
Common factor that has no rela-
tion with abnormality source.
1
The unit of former address
does not exist as address
switch has changed while the
unit was energized.
2
Voltage drop and weak signal
which lead communication
error are caused by over-range
transmission wire.
• Maximum distance··· 656 ft [200 m]
• Remote controller line (39 ft [12m])
3
Voltage drop and weak signal
which lead communication
error are caused by type-
unmatched transmission wire.
Type····
With shield wire-
CVVS, CPEVS
With normal wire (no shield)-
VCTF, VCTFK, CVV
CVS, VVR, VVF, VCT
Diameter····1.25mm
2
[AWG16]
or more
4
Voltage drop and weak signal
which lead communication
error are caused by over-
numbered units.
5
Accidental malfunction of
abnormality-detected controller
(noise, thunder surge)
6
Defective of abnormality-
detected controller
2. If displayed address or attribute is out-
door unit, indoor unit detects abnormality
when indoor unit transmitted to outdoor
unit and there was no reply (ACK).
1
Contact failure of transmission
wire of outdoor unit or indoor unit
2
Disconnection of transmission
connector (CN2M) of outdoor
unit
3
Defective transmitting receiving
circuit of outdoor unit or indoor
unit
Always try the following when the error
“A7” occurs.
1
Turn off the power supply of outdoor unit
and indoor unit and FRESH MASTER or
LOSSNAY at the same time for 2 minutes or
more, and turn the power on again. If mal-
function was accidental, the unit returns to
normal.
2
Check address switch of abnormality-detect-
ed address.
3
Check disconnection or looseness of abnor-
mality-detected transmission wire (terminal
block and connector)
4
Check if tolerance range of transmission wire
is not exceeded.
5
Check if type of transmission wire is correct
or not.
If there were some troubles of
1
–
5
above,
repair the defective, then turn off the power
supply of outdoor unit and indoor unit and
FRESH MASTER or LOSSNAY at the same
time for 2 minutes or more, and turn the power
on again.
• If there was no trouble with
1
–
5
above in
single refrigerant system (one outdoor unit),
controller of displayed address or attribute is
defective.
• If there was no trouble with
1
–
5
above in dif-
ferent refrigerant system (2 or more outdoor
units), judge with
6
.
6
If address of abnormality source is the
address that should not exist, there is the
unit that memorizes nonexistent address
information. Delete unused address informa-
tion with manual setting function of remote
controller.
Only the system FRESH MASTER or
LOSSNAY are connected to, or the system
that is equipped with group setting of differ-
ent refrigerant system.
If there was no trouble with
1
–
6
above,
replace the controller board of displayed
address or attribute.
If the unit does not return to normal, multi-con-
troller board of outdoor unit may be defective
(repeater circuit).
Replace multi-controller board one by one to
check if the unit returns to normal.
3. If displayed address or attribute is indoor
unit, remote controller detects abnormal-
ity when remote controller transmitted to
indoor unit and there was no reply (ACK).
1
During group operation with
indoor unit of multi- refrigerant
system, if remote controller
transmit to indoor unit while
outdoor unit power supply
of one refrigerant system is
turned off or within 2 min-
utes of restart, abnormality is
detected.
2
Contact failure of transmission
wire of remote controller or
indoor unit
3
Disconnection of transmission
connector (CN2M) of indoor unit
4
Defective transmitting receiving
circuit of indoor unit or remote
controller
Check Code