Haier 2U40S2SM1FA, Service Manual, Page: 22 / 73

7.1.4 The outdoor fan control (exchange fan)
When the fan is changed among every airflow speed (including stop blowing), in order to avoid
the airflow speed from skipping frequently, it must be kept under each mode for over 30 seconds.
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).
When Tpg_indoor ice_temp_1 , the frequency of the compressor decreases at the speed of
1HZ/1second.
When Tpg_indoor
ice_temp_2 , the frequency of the compressor decreases at the speed of
1HZ/10seconds.
When Tpg_indoor begins to rise again, and ice_temp_2 =Tpg_indoor = ice_temp_3 , the
frequency of thecompressor doesn’t change.
When ice_temp_3 Tpg_indoor ice3 , the frequency of the compressor increases at
the speed of 1HZ/10seconds.
For example, Tpg_indoor<= 0
last for 2 minutes, and then the outdoor unit will stop, and report
underload malfunction, but don’t send malfunction report to the indoor.
The compressor stops for more than 3 minutes, Tpg_indoor> ice2 , the compressor
recovers.
Temperature protection of the outdoor refrigerating coil
When the defrosting temperature and the sensor’s temperature are higher than 64 , the
frequency of the compressor decreases 1hz/10seconds.
When the temperatures are lower than 64 and higher than 60 , keep
the frequency of the compressor. When the temperatures are higher than 70 , relieve the
defrosting temperature protection.
11 //ice5
9
y l w o l s g n i s a e r c n I 3 + 3 _ p m e t _ e c
8 //ice2
Keeping the frequency
ice_temp_3
7
6
ice_temp_2
3
Decreasing slowly
ice_temp_1
3
Decreasing rapidly ice_temp_1
1
Stop
7.1.3.5
7.1.3.6
Functions and control
Domestic air conditioner
20