60
Installation and Maintenance
Service Manual
32
Drop
malfunction
of DC busbar
voltage
U3
Flash
20 times
every 3s
□
■
■
■
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;
33
Low voltage
protection of
DC bus bar
PL
Flash
21 times
every 3s
□
■
■
□
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;
34
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;
35
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;