Service manual

SiUS28-902_a Troubleshooting by Indication on the Remote Controller
Troubleshooting 136
3.39 “U5” Malfunction of Transmission between Remote
Controller and Indoor Unit
Remote
Controller
Display
U5
Applicable
Models
AII indoor unit models
Method of
Malfunction
Detection
In case of controlling with 2-remote controller, check the system using microcomputer is signal
transmission between indoor unit and remote controller (main and sub) is normal.
Malfunction
Decision
Conditions
Normal transmission does not continue for specified period.
Supposed
Causes
 Malfunction of indoor unit remote controller transmission
 Connection of two main remote controllers (when using 2 remote controllers)
 Defect of indoor unit P.C.B.
 Defect of remote controller P.C.B.
 Malfunction of transmission caused by noise
Troubleshooting
Caution
Be sure to turn off the power switch before connecting or disconnecting
the connector, or parts could be damaged.
NO
YES
YES
NO
Replace indoor unit P.C.B.
Set one remote controller to
"SUB"; turn the power supply
off once and then back on.
There is possibility of
malfunction caused by noise.
Check the surrounding area
and turn on again.
NO
NO
Using
2-remote controllers
control.
All indoor
P.C.B. microcomputer
monitors blink.
YES
Multi-core
cable is used for the
indoor unit remote controller
transmission
wiring.
Operation
returns to normal when
the power is turned off
momentarily.
YES
YES
SS1 of
both remote controllers
is set to "MAIN."
NO
Switch to double-core
independent cable.
replacement
Defect of remote controller
P.C.B. or indoor u
nit P.C.B.
Replace whichever is
defective.