Communication Error With Communication Processor; No Ack Signal - Mitsubishi Electric PUHZ-RP250YHA2 Service Manual

Error Code Abnormal point and detection method
Communication error with communica-
tion processor
Defective communication between unit
processor and transmission processor
Note) The address and attribute displayed
A6 at remote controller indicate the con-
(6606) troller that detected abnormality.

NO ACK signal

1. Transmitting side controller detects
abnormality if a message was transmit-
ted but there is no reply (ACK) that a
message was received. Transmitting
side detects abnormality every 30 sec-
onds, 6 times continuously.
Note) The address and attribute displayed
at remote controller indicate the con-
troller that did not reply (ACK).
A7
(6607)
2. If displayed address or attribute is out-
door unit, indoor unit detects abnormality
when indoor unit transmits signal to out-
door unit and there was no reply (ACK).
3. If displayed address or attribute is indoor
unit, remote controller detects abnormal-
ity when remote controller transmits sig-
nal to indoor unit and there was no reply
(ACK).
Case
Data of transmission proces-
sor or unit processor is not
transmitted normally because
of accidental trouble such as
noise or thunder surge.
Address forwarding from unit
processor is not transmitted
normally because of defective
transmission processor hard-
ware.
Common factor that has no rela-
tion with abnormality source
The unit of former address
does not exist as address
switch has changed while the
unit was energized.
Extinction of transmission wire
voltage and signal is caused by
over-range transmission wire.
• Maximum distance·······200m
• Remote controller line (12m)
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····1.25mm or more
2
Extinction of transmission wire
voltage and signal is caused
by over-numbered units.
Accidental malfunction of
abnormality-detected controller
(noise, thunder surge)
Defective of abnormality-gen-
erated controller
Contact failure of transmission
wire of outdoor unit or indoor
unit
Disconnection of transmission
connector (CN2M) of outdoor
unit
Defective transmitting receiving
circuit of outdoor unit or indoor
unit
During group operation with
indoor unit of multi-refrigerant
system, if remote controller
transmits signal to indoor unit
while outdoor unit power sup-
ply of one refrigerant system
is turned off or within 2 min-
utes of restart, abnormality is
detected.
Contact failure of transmission
wire of remote controller or
indoor unit
Disconnection of transmission
connector (CN2M) of indoor
unit
Defective transmitting receiving
circuit of indoor unit or remote
controller
36
Judgment and action
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. System returns nor-
mally if abnormality was accidental malfunc-
tion. If the same abnormality generates again,
abnormality-generated controller may be defec-
tive.
Always try the followings when the error
"A7" occurs.
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 mal-
function was accidental, the unit returns to
normal.
Check address switch of abnormality-gener-
ated address.
Check disconnection or looseness of abnor-
mality-generated or abnormality-detected
transmission wire (terminal block and con-
nector)
Check if tolerance range of transmission wire
is not exceeded.
Check if type of transmission wire is correct
or not.
If there were some trouble of
repair the defect, then turn off the power sup-
ply 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
single refrigerant system (one outdoor unit),
controller of displayed address or attribute is
defective.
• If there was no trouble with
ferent refrigerant system (2 or more outdoor
units), judge with .
If address of abnormality source is the
address that should not exist, there is the
unit that memorizes nonexistent address
information. Delete useless 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 -
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
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above, replace