The minimum frequency is displayed when indoor coil- pipe temperature is lower than 2ºC and coil-pipe 
temperature is above -0.5ºC. 
When thermal conversion temperature is lower than 0.5ºC, selecting 3 minutes stand-by status. 
When indoor coil-pipe temperature is 2.1ºC, the compressor restarts. 
During trial running, the low-load protection control can be overlooked.   
1.1.7.2 High-load protection 
During heating running, if the indoor coil-pipe temperature is too high, the compressor must be stopped for 
protection to prevent it from damaging due to the system overheating. See the following figure for details: 
 
Thermal conversion temperature 
74.7ºC  (undetermined) 
70.3ºC  (undetermined) 
65.1ºC  (undetermined) 
62.2ºC  (undetermined) 
52.9ºC  (undetermined) 
51.6ºC  (undetermined) 
47.1ºC (undetermined) 
 
 
 
 
 
 
 HSU-12H03/(BP)1 
Indicate 
frequency 
Stop   C       3 minutes standby        C      B        A         B   C    Stop
D 
E
 
 Parameters 
Frequency A  Fpqhheat0  110Hz 
Frequency B  Fpqhheat1  100Hz 
Frequency C  Fpqhheat2  80Hz 
Frequency D  Fpqhheat3  40Hz 
Frequency D  Fpqhheat4  30Hz 
When high-load protection is limited to act twice within 30 minutes, it is high-load protection alarm. 
When indoor coil pipe temperature is lower than 45ºC, it comes back to normal control. 
The frequency of high load protection is priority. 
 
 
 
 
1.1.7.3 Compressor discharge temperature protection 
When air conditioner is running, the discharge temperature need not to be detected within the first 10 minutes and 
starts to detect after 10 minutes. If the detected temperature is found too high, the compressor shall be protected 
from damaging by decreasing frequency or stopping, see the following figure for details: 
 
Model:
HSU-09H03/(BP)1
HSU-12H03/(BP)1Domestic Air Conditioner
 
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