Mitsubishi Electric CITY MULTI PUHY-400YMF-B, Service Handbook

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6607
Meaning, detecting method
No ACK error When no ACK signal is detected in 6 continuous times with 30 second interval by transmission side
controller, the transmission side detects error.
Note) The address/attribute shown on remote controller indicates the controller not providing
the answer (ACK).
Checking method & countermeasure
System
compo-
sition
Generating
unit address
Display of
trouble
Detecting
method
Cause
(1) Single refr
iger
ant system
1 Outdoor
unit
(OC)
2 Indoor
unit (IC)
3
Remote
control-
ler (RC)
Remote
controller
(RC)
Remote
controller
(RC)
Remote
controller
(RC)
No reply
(ACK) at IC
transmission
to OC
No reply
(ACK) at RC
transmission
to IC
No reply
(ACK) at IC
transmission
to RC
1) Poor contact of transmission line of OC or IC.
2) Damping of transmission line voltage/signal by
acceptable range of transmission wiring ex-
ceeded.
Farthest : Less than 200 m
Remote controller wiring: Less than 10 m
3) Erroneous sizing of transmission line (Not
within the range below).
Wire diameter: 1.25 mm
2 or more
4) Faulty control circuit board of OC
1) When IC unit address is changed or modified
during operation.
2) Faulty or slipping off of transmission wiring of
IC.
3) Slipping off of IC unit connector (CN2M).
4) Faulty IC unit controller.
5) Faulty remote controller.
6) The transmission booster is defective, has dis-
connected wires, or the power has been cut-
off.
1) Faulty transmission wiring at IC unit side.
2) Faulty transmission wiring of RC.
3) When remote controller address is changed
or modified during operation.
4) Faulty remote controller.
5) The transmission booster is defective, has dis-
connected wires, or the power has been cut-
off.
Shut down OC unit power source, and
make it again.
It will return to normal state at an ac-
cidental case.
When normal state can not be re-cov-
ered, check for the 1) ~ 4) of the cause.
Shut down both OC and IC power so-
urces simultaneously for 5 minutes or
more, and make them again.
It will return to normal state at an acci-
dental case.
When normal state can not be re-cov-
ered, check for the 1) ~ 6) of the cause.
Shut down OC power sources for 5 min-
utes or more, and make it again.
It will return to normal state at an acci-
dental case.
When normal state can not be re-cov-
ered, check for the 1) ~ 5) of the cause.