45
Technical Information
Service Manual
Frequency Reducing Phase Current
], and the compressor have stopped working 
for 3 min, the machine shall be allowed to operate;
4. If the overcurrent protection of compressor phase current 
continuously occurs for six times, it should not be resumed 
automatically, and you should press the ON/OFF button to 
resume. During the process of running, if the running time of 
compressor exceeds the [t 
Clearing Time of Compressor Phase Current Times
] , the 
overcurrent protection is cleared to recount.
(12) Starting-up Failure Protection for Compressor
Stop the compressor after its starting-up fails, restart it after 20s if 
the fault doesnt shows, and if they are all failing for the successive 
start 3 times, it shall be reported as Starting-up Failure, and then 
restart up it after 3 min. When it still not be able to operate through 
carry out the above process for 5 times, it is available if press ON/
OFF. And the compressor should be cleared the times after it run 
2 min.
(13) Out-of-Step Protection for Compressor
The out-of-step protection signal should be detected immediately 
after starting-up compressor, and once find the out-of-step 
protection signal, the out-of-step protection shall be stopped; if 
it can run for lasting power turn-off 3 min, the machine shall be 
allowed to operate. If it still cant run automatically when the out-
of-step protection for compressor happens to stop working for 6 
times in succession, it needs to press ON/OFF to operate. And if 
the running time is more than 10 min, the power turn-off times for 
out-of-step protection shall be cleared and recounted.
(14) Voltage Abnormity Protection for DC Bus
To detect voltage abnormity protection for dc bus after completing 
the pre-charge:
1.Over-High Voltage Protection for DC Bus:
If it found the DCbus voltage U
DC
 >[UDC
 Jiekuangchun Protection
], turn off 
PFC and stop the compressor at once, and it shall show the DC 
over-high voltage failure; it should clear out the failure when the 
voltage dropped to U
DC
 <[UDC 
Jiekuangchun Recovery
] and the compressor 
stopped for 3 min.
2.Over-Low Voltage Protection for DC Bus:
If it found the DC bus voltage U
DC
 <[U
DC Wantuochun Protection
], turn off 
PFC and stop the compressor at once, and it shall show the DC 
over-low voltage; and it should clear out the failure when the 
voltage raised to U
DC
 >[U
DC Wantuochun Recovery
] and the compressor 
stopped for 3 min.
3.To  detect  voltage  abnormity  protect  for  DC  bus  when 
getting electricity:
If it found the DC bus voltage U
DC
 >[U
DC——Over-High Voltage
], turn off 
the relay at once, and shows voltage abnormity failure for DC 
Bus. And the failure cant recover except to break off and get the 
electricity.
(15) Abnormity Protection for Four-way Valve
Under the model of heating operation in good condition: the 
compressor is detected [T
Inner Tube
 <(T
Inner Ring
-T
 Abnormity Temperature Difference 
For Four-Way Valve Reversion
)], during the running, it should be regarded as 
four-way valve reversion abnormity. And then it can run if stop 
the reversion abnormity protection for four-way valve 3 min; and 
if it still cant run when the reversion abnormity protection for four-
way valve happens to stop working for 3 times in succession, it is 
available if presses ON/OFF.
Attention: the protection shall be shielded during the testing mode 
and defrosting process, and it shall be cleared out the failure and 
its times immediately when turning off or delivering wind / cooling / 
dehumidifying mode conversed (the inverted mode dont clear out 
the failure when it cant recover to operate).
(16) PFC Protection
1. After start up the PFC, it should detect the protection signal of 
PFC immediately; under the condition of PFC protection, it should 
turn off the PFC and compressor at one time;
2. It shows the failure is cleared out if PFC Protection stopped 
working 3 min and recovers to run automatically;
3. If it still cant run when it occurs PFC protection for 3 times in 
succession, it is available if presses ON/OFF; and clear the PFC 
Protection times when start up PFC for 10min.
(17) Failure Detection for Sensor
1. Outdoor Ambient Sensor: detect the failure of sensor at all 
times.
2. Outdoor Tube Sensor: You should not detect the failure of 
outdoor tube sensor within 10 minutes heating
operation compressor except the defrosting, and you could detect 
it at other time.
3. Outdoor Exhaust Sensor:
(a) The compressor only detect the sensor failure after it start up 3 
min in normal mode;
(b) It should detect the exhaust sensor failure immediately in the 
testing mode.
4. Module Temperature Sensor:
(a) Short-Circuit Detection: the compressor should be detected 
immediately when the module temperature
sensor occurs short-circuits;
(b) Open-Circuit Detection: the compressor should be detected on 
open-circuit when it runs 3min (it neednt 30s
avoiding the module over-heated).
(c) Detect the sensor failure at all times in the testing mode.
5. Disposal for Sensor Protection
(1) When the short-circuit of sensor is detected within 30s, It is 
regarded as the temperature of sensor over-high (or infinitely 
high), and now according to the over-high sensor, the machine 
should carry out the corresponding protection to stop working, 
and show the corresponding temperature shutdown protection 
and sensor failure at the same time (for example: the compressor 
stops immediately when the outdoor tube sensor short-circuit, and 
the machine shall show the overload protection and outdoor tube 
sensor failure).
(2) When the open-circuit of sensor is detected within 30s, The 
protection shall be stopped and it shall show the corresponding 
sensor failure.
6. Electric Heating Function of Chassis
(1) When Toutdoor amb.≤32ºF , the electric heating of chassis will 
operate;