Mitsubishi Electric PUZ-A12NKA7 Service Manual page 40

Check code Abnormal points and detection method
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).
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).
A7
(6607)
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).
4. If displayed address or attribute is remote
controller,
Indoor unit detects abnormality when
indoor unit transmitted to remote control-
ler and there was no reply (ACK).
OCH636A
Case
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 Extinction of transmission wire
voltage and signal is caused by
over-range transmission wire.
• Maximum distance · ····· 656 ft
[200 m]
• Remote controller line . . (39ft
[12 m])
3 Extinction of transmission wire
voltage and signal is 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 · ···1.25 mm 2 [AWG16]
or more
4 Extinction of transmission wire
voltage and signal is caused by
over-numbered units.
5 Accidental malfunction of
abnormality-detected controller
(noise, lightning surge)
6 Defective of abnormality gener-
ated controller
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
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 minutes 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
1 During group operation with
indoor unit of multi- refrigerant
system, if indoor unit transmit
to remote controller while out-
door unit power supply of one
refrigerant system is turned off
or within 2 minutes 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
40
judgment and action
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 gener-
ated address.
3 Check disconnection or looseness of abnor-
mality generated or abnormality detected
transmission wire (terminal block and connec-
tor)
4 Check if tolerance range of transmission wire
is not exceeded.
5 Check if type of transmission wire is correct or
not.
If the cause of trouble is in 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 the cause of trouble is not in 1–5 above in
single refrigerant system (one outdoor unit),
controller of displayed address or attribute is
defective.
• If the cause of trouble is not in 1–5 above in
different 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 informa-
tion. Delete useless address information 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 different
refrigerant system.
If the cause of trouble is not any of 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.
Continued to the next page.