69
Installation and Maintenance
Service Manual
34
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;
35
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 units main
board;
2. Replace outdoor units
main board AP1;
36
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
units main board is not
enough; screws havent
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 units main
board;
2. Replace outdoor units
main board AP1;
37
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 units main
board;
3. Replace outdoor units
main board AP1;
