Haier HSM18HEKC03/R2 Service Manual page 26

5.2.3 The control of the outdoor electronic expansion valve
When starting the compressor: the opening size of the valve must be guaranteed to have entered into
the standard opening size, and then the compressor can be started.
When refrigeration is in vain (the machine is shut down or is in the state of retrograde operation), the
opening size of the expansion valve of the indoor unit is 5 steps;
When heating is in vain, the opening size of the expansion valve of the indoor unit is 55 steps;
When the outdoor unit is shut down, the valve is opened completely for 2 minutes, and then begin
initialization.
The scope of refrigerationg valve
The scope of heating valve
The valves are adjusted according to the degree of superheat —SHa
5.2.4 Four way control
For the details of defrosting four-way valve control, see the defrosting process.
Four way working in other ways:
Under the mode of heating, open the four-way valve, when the compressor is not started or changed
to non-heating mode, make sure the compressor is stoped for 2 minutes, and then close the four-way
valve.
5.2.5 The outdoor defrosting control
A.The conditions for entering into defrosting mode
When starting running heating, the compressor continuously runs for over 10 minutes, after running
for 45 minutes in all (defrosting is ended or when entering into refrigeration mode, clear the
compressor's cumulative run time), through detecting the defrosting sensor TCS detect the defrosting
situation of the heat exchanger of the outdoor unit and the outdoor environment temperature sensor
TA, and meeting the following conditions continuously for 2 minutes, the machine enters into the
defrosting operation:
TCS≤C×TA α
α is determined as the following according to the data of EEPROM:
C selcet if Tao 0
The temperature limitation for entering into defrosting mode -15 ≤C×TA α≤-5
B.Defrosting time interval
When the result of C×TA α is in the scope of -15 ≤C×TA α, the interval between two defrostings is
45 minutes (the time interval which is in 57 digits in EEPROM can be adjusted
When the result of C×TA α is in the scope of C×TA α<-15 , the time interval between two
defrostings is 65 minutes.
C.Defrosting operation
When starting defrosting, the compressor stops for 1 minute at first, and the outdoor fan is running,
after 55 seconds, the four-way valve is off.
When the compressor is started, the outdoor fan is stoped, the compressor stops for 30 seconds at
the conditions of 58HZ, and then runs towards the target frequency—88HZ.
During defrosting period, the protections, such as current of the compressor, compressor's blowing
HSM18HEKC/HRAC03/R2(DB)HUM18HC03/R2(DB)-SM
C=0.8;if Tao≥0
60-----480 steps
90-----480 steps
C=0.6 αis read from EEPROM Normal State: α=6
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Function and control
SHa.
Domestic Air Conditioner