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Checkcode
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
message was received. Transmitting side
detects abnormality every 30 seconds, 6
times continuously.
Note: The address and attribute displayed
at remote controller indicate the
controller that did not reply (ACK).
2. If displayed address or attribute is
outdoor unit, indoor unit detects
abnormality when indoor unit transmits
signal to outdoor unit and there was no
reply (ACK).
A7
(6607)
3. If displayed address or attribute is indoor
unit, remote controller detects abnormality
when remote controller transmits signal
to indoor unit and there was no reply
(ACK).
4. If displayed address or attribute is remote
controller, indoor unit detects abnormal-
ity when indoor unit transmits signal to
remote controller and there was no reply
(ACK).
OCH653C
Cause
Common factor that has no relation 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 ....... 200 m
• Remote controller line .. (12 m)
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
or more
2
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-occured
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 transmits signal 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 transmits signal to remote control-
ler 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 connec-
tor (CN2M) of indoor unit
4 Defective transmitting receiving circuit
of indoor unit or remote controller
47
Judgment and action
Always try the following when the
error "A7" occurs.
1 Turn off the power supply of outdoor
unit, indoor unit and FRESH MASTER
or LOSSNAY at the same time for 2
minutes or more, and turn the power
on again. If malfunction was accidental,
the unit returns to normal.
2 Check address switch of abnormality-
occured address.
3 Check disconnection or looseness of
abnormality-occured or abnormality-
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 defect, then turn off the
power supply of outdoor unit, 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 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 information. Delete unused
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 there was no trouble with 1–6 above,
replace the controller board of displayed
address or attribute.
If the unit does not return normally, multi-
controller board of outdoor unit may be
defective (repeater circuit).
Replace multi-controller board one by
one to check if the unit returns normally.
Continued to the next page.
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