Haier 1U71SABFRA Service Manual page 22

7.1.5.4 Antifreezing protection of the indoor heat exchanger
When refrigerating/heating, prevent freezing.
Tpg_indoor is the minimum value of the effective indoor unit (start it and it is in accord with the running state).
9
ice_temp_4
ice_temp_3 7
ice_temp_2 5
ice_temp_1 3
0
When Tpg_indoor
1HZ/1second.
When Tpg_indoor
1HZ/10seconds.
When Tpg_indoor begins to rise again, and ice_temp_2 Tpg_indoor
thecompressor doesn't change.
When ice_temp_3 Tpg_indoor ice_temp_4 , the frequency of the compressor increases at the speed of
1HZ/10seconds.
For example, Tpg_indoor 0
malfunction, but don't send malfunction report to the indoor.
The compressor stops for more than 3 minutes, Tpg_indoor> ice_temp_4 , the compressor recovers.
Increasing slowly
Decreasing slowly
Decreasing rapidly
Stop
ice_temp_1 , the frequency of the compressor decreases at the speed of
ice_temp_2 , the frequency of the compressor decreases at the speed of
last for 2 minutes, and then the outdoor unit will stop, and report underload
11 //ice_temp_4+2
9 //ice_temp_3+2
Keeping the frequency
6
ice_temp_1
20
Functions and control
ice_temp_3 , the frequency of
Domestic air conditioner