Haier AU282FHAHA Service Manual page 41

9.3 Defrost operation Flow Chart
1. The compressor operates heating over 25 minutes, after meeting the defrosting condition, it is
permitted to enter defrosting. Defrosting process is unit-stop defrosting mode. Determining
condition of defrosting is as follows:
Unit-stop defrosting:
(1) When outdoor ambient temperature Ta is less than 2 , Ta-Te (defrosting sensor
temperature) is more than 9 , and keeping over 2 minutes, enter unit-stop
defrosting.
(2) Outdoor ambient temperature >2 , pipe coil temperature <15
defrosting.
(3) If meeting the above condition, enter unit-stop defrosting.
(4) First the outdoor unit sends defrosting signal to indoor unit, after receiving signal, the
indoor unit acts according to the following condition:
a. The running fan motor of indoor unit for heating stops; the electronic expansion valve
does not change.
b. The running fan motor of indoor unit for turning off unit stops; the electronic expansion
valves of indoor unit are totally open.
(5) The defrosting action of outdoor unit:
a. The electronic expansion valves are totally open; compressor stops; 4-way valve keeps
in heating state; fan motor of outdoor unit is turned off.
b. After 45 seconds, 4-way valve is closed; compressor operates in 58Hz frequency.
c. After the compressor has operated in 58Hz for 30 seconds, it will operate in 120Hz.
Only after 3 minutes have elapsed in defrosting state can it quit from this operation.
(6) The condition of quitting from defrosting:
a. After entering defrosting for 3 minutes, test the temperature of defrosting sensor,
continue for 1 minute over 12 , then quit from defrosting.
b. Or after continuously defrosting for over 9 minutes, then quit from defrosting.
c. Discharging air pressure over 2MPaG (G stands for this pressure is piezometer
pressure), defrosting over 1 minute.
(7) Actions of indoor & outdoor unit when quitting from defrosting:
a. Compressor stops 43 seconds, fan motor of outdoor unit enter set fan speed according
to the state before entering defrosting.
b. After stop 45 seconds, compressor starts, simultaneously 4-way valve enters heating.
c. The open state of outdoors electronic expansion valve enters the state before entering
defrosting.
d. Indoor fan speed works in anti-cool Air State.
e. The open state of indoors electronic expansion valve is controlled to start adjusting
after defrosting 4 minutes.
(8) The protective treatment in defrosting:
a. Pressure switch not protected
b. The protective function of any temperature sensors is cancelled.
c. After finishing defrosting, discharging air temperature and adjustment of expansion
valve open state, current protection etc. work should be carried out according to the
state when compressor is just turned on.
Commercial Air Conditioner
- 40 -
Model: AU282FHAHA
enter unit-stop
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