Haier U Series Service Manual page 24

5.2.3 Outdoor Electronic Expansion Valve Control
Energization Initial Operation:
Valve Complete Off Operation
Valve operation after compressor startup and shutdown:
Compressor Startup: Opening of valve must ensure restart of compressor when reaching benchmark
opening.
Compressor Shutdown: It ensures complete off of valve after compressor shuts down.
Valve operation when compressor is running
nd
Around the 2
ambient temperature and corresponding frequency.
Overheat benchmark will be adjusted if air discharge temperature is too high or too low in cooling or
heating mode.
5.2.4 Four-way Valve Control
In heating mode, four-way valve is on. If compressor is off or is switched to non-heating mode,
four-way valve ensures that it is off at least 2 minutes after compressor shuts down.
5.2.5 Outdoor Defrosting Control
The unit will enter defrosting mode when compressor starts up and operates for 10 minutes
continuously in heating mode or after compressor runs for an accumulated time of 45
Defrosting
minutes (Upon completion of defrosting or when switched to cooling mode, compressor
Mode Entry
accumulatedoperation time will be cleared) and when 2 minutes' continuous checking by defrosting
Conditions
sensor TE (check frosting condition of outdoor unit heat exchanger) and outdoor ambient temperature
sensor TA meets the following conditions:
Defrosting entry temperature control :-15
When data calculated by C TA
Defrosting
Time Interval interval between two defrosting cycles is 45 minutes.
When data calculated by C
between two defrosting cycles is 65 minutes.
Defrosting When defrosting begins, compressor will stop for one minute, external fan is running and Operation
50s later, four-way valve will be off.
When compressor starts, external fan will be off, compressor will run at 58HZ for 60s then move on to
target frequency of 88HZ.
During defrosting, compressor current and air discharge overheat protection features are effective.
During defrosting, if compressor shuts down due to activation of protection feature or due to
malfunction, it will resume after 3 minutes. In the unit is still within defrosting cycle, it will resume
defrosting and startup of compressor will be based on the rule for defrosting startup. (The unit will exit
defrosting mode and handle fault in the event of 3 consecutive restart failures.)
On entering defrosting, it must guarantee that compressor will operate for a minimum of 2 minutes in
defrosting mode before exit.
When one of the following conditions is met, defrosting operation will be switched to
Defrosting
Exit Condition heating operation.
HSU-09,12H03/U(DBPZXF)
minute after compressor startup, valve opening can be adjusted based on various outdoor
TE C TA
Among which: C:TA 0
TA
C=x
TA 0 C=y
C TA -5
falls into the range of -15
falls into the range of C
21
Functions and Control
C TA , time
TA <-15 , time interval
Domestic Air Conditioner