Service Manual

Troubleshooting by Error Codes SiUS281811E
260 Part 6 Service Diagnosis
Note(s)
4.59 System Abnormality, Refrigerant System Address
Undefined
Error Code UH
Applicable
Models
All indoor units
All outdoor units
Method of Error
Detection
System detects an indoor unit whose address is not defined by automatic address function.
Automatic address refers to the automatic designated address of indoor unit and outdoor unit
when connected to the power after installation or wiring replacement (with the RESET (BS5)
button pressed for more than 5 seconds).
Error Decision
Conditions
The error decision is made as soon as the abnormality aforementioned is detected.
Supposed
Causes
 Improper connection of transmission wiring between indoor-outdoor units
 Defective indoor unit PCB
 Defective outdoor unit main PCB (A1P)
Troubleshooting
1. Refer to installation manual for correct "indoor unit and outdoor unit connection wiring".
Caution
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.
NO
YES
YES
After fixing incorrect wiring,
press and hold the RESET
(BS5) button on the outdoor
unit main PCB for 5 seconds.
 The unit will not run for up to
12 minutes.
Normal.
NO
NO
Does a UH error
occur for all indoor
units in the system?
YES
NO
YES
Replace the indoor unit PCB.
Replace the outdoor unit main
PCB (A1P).
Press and hold the RESET
(BS5) button on the outdoor
unit PCB for 5 seconds
Does
an error
occur even after
12 minutes elapses
from the time when
electricity is introduced
to indoor and
outdoor
units?
Is
electricity
being introduced
for the first time after
installation or after an indoor
or outdoor unit main
PCB has been
replaced?
Is indoor-outdoor unit
transmission wiring
normal? (1)