Nobu NBL4-09IDU32 Service Manual page 55

Service Manual
(3) High temperature and overload protection diagnosis (AP1 hereinafter refers to the control board of the outdoor unit)
Mainly detect:
●Is outdoor ambient temperature in normal range?
●Are the outdoor and indoor fans operating normally?
●Is the heat dissipation environment inside and outside the unit good?
Fault diagnosis process:
Is outdoor ambient temperature higher than 53?
Installation and Maintenance
90
Overheat and high
temperature protection
No
20 minutes after the complete
unit is powered off.
Is heat dissipation of the indoor unit
and outdoor unit abnormal?
No
Does the outdoor fan work normally?
Yes
Replace the
control panel AP1
End
Normal protection, please operate
Yes
it after the outdoor ambient temp-
erature is normalized.
Improve the heat
Yes
dissipation environ-
ment of the unit
1. Check if the fan terminal OFAN
is connected correctly
No
2. Resistance between any two
terminals is measure by an ohm
gauge and should be less than 1K
Ohm.
Replace the fan
capacitor C1
Replace the
outdoor fan
Service Manual
Installation and Maintenance
51