54
Installation and Maintenance
Service Manual
31
Drop
malfunction
of DC busbar
voltage
U3
□
■
■
■
During cooling and
drying operation,
compressor and
outdoor fan stop while
indoor fan operates.
During heating
operation, all loads
stop.
Power voltage
is unstable, big
fluctuation.
1. Check whether
power supply
network is
abnormal;
32
Low voltage
protection of
DC bus bar
PL
□
■
■
□
During cooling and
drying operation,
compressor and
outdoor fan stop while
indoor fan operates.
During heating
operation, all loads
stop.
The voltage at
positions L and N on
wiring board (XT) is
lower than 150 VAC
1. Check whether
power supply
network is
abnormal;
Hardware malfunction
of outdoor unit's main
board;
2. Replace outdoor
unit's main board
AP1;
33
Limit/
decrease
frequency due
to module
temperature
protection
EU
■
■
■
☆
All loads operates
normally, while
operation frequency
of compressor
decreases.
Radiating grease
on IPM module of
outdoor unit's main
board is not enough;
screws haven't been
fixed tightly;
1. After the system
is de-energized
for 20min and
discharge, check
whether radiating
grease on IPM
Module of outdoor
control board AP1 is
enough and whether
the radiating is fixed
tightly;
Hardware malfunction
of outdoor unit's main
board;
2. Replace outdoor
unit's main board
AP1;
34
4-way valve is
abnormal
U7
■
□
☆
□
This malfunction
occurs under heating
operation: all loads
stop.
Power voltage is lower
than AC175V
Wiring terminal 4V is
loose or broken
2. After de-
energization, insert
OVC-COMP tightly
or replace wiring
Hardware malfunction
of outdoor unit's main
board;
3. Replace outdoor
unit's main board
AP1;
