34
Installation and Maintenance
Service Manual
NO.
Malfunction
Name
Display Method of Indoor Unit
Display Method of Outdoor 
Unit
A/C status Possible Causes 
Dual-8
Code
Display
Indicator Display (during 
blinking, ON 0.5s and OFF 
0.5s)
Indicator has 3 kinds of 
display status and during 
blinking, ON 0.5s and OFF 
0.5s
Operation
Indicator
Cool
Indicator
Heating
Indicator
Yellow
Indicator
Red
Indicator
Green
Indicator
43
Malfunction of 
phase current
detection 
circuit for 
compressor
U1
During cooling and drying
operation, compressor will stop
while indoor fan will operate;
During heating operation, the
complete unit will stop
Replace outdoor control panel AP1
44
Malfunction of 
voltage
dropping for
DC bus-bar
U3
During cooling and drying
operation, compressor will stop
while indoor fan will operate;
During heating operation, the
complete unit will stop
Supply voltage is unstable
45
Malfunction 
of complete 
units current 
detection
U5
During cooling and drying
operation, the compressor will
stop while indoor fan will 
operate; 
During heating operating, 
the complete unit will stop 
operation.
Theres circuit malfunction on 
outdoor units control panel AP1, 
please replace the outdoor units 
control panel AP1.
46
The four-way
valve is
abnormal
U7
If this malfunction occurs 
during heating operation, 
the complete unit will stop 
operation.
1.Supply voltage is lower than 
AC175V;
2.Wiring terminal 4V is loosened or 
broken;
3.4V is damaged, please replace 
4V.
47
Frequency 
limiting 
(power)
OFF 3S
and blink
13 times
48
Compressor 
is open-
circuited
OFF 3S
and blink
once
49
The 
temperature 
for turning 
on the unit is 
reached
OFF 3S
and blink
8 times
50
Frequency 
limiting 
(module 
temperature)
OFF 3S
and blink
11 times
51
Malfunction 
of zero-cross 
detection 
circuit
U8 The complete unit stops
1.Power supply is abnormal;
2.Detection circuit of indoor control 
mainboard is abnormal.