Haier 1U71S2SG1FA Service Manual page 220

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60℃
Low Pressure Protection (Multi)
(1) When compressor is running, if output signal of low pressure switch is low level: 0 for 1 minute continously,
compressor will stop,outdoor alarms. The alarm can be resumable. If in 60 minutes, the failure occurs 3 times, the
failure can be confirmed and send failure code to indoor.
(2) When compressor no running, if output signal of low pressure switch is low level: 0 for 30 seconds continously,
alarm will occur.
• When unit stops, the reason that system still checks the low pressure : in a long time stop, make protection for
the compressor on the condition of great refrigerant leakage.
• The reason that low pressure switch action time is 30 seconds: when compressor stops, low pressure does not
change, so it will be shorter than the set time in operation.
(3) When compressor starts up, in 8 minutes, low pressure switch signal will be shielded.
(4) In defrosting, low pressure switch will be shielded.
(5) In oil return procedure, low pressure switch will be shielded.
(6) In the refrigerant discharging procedure after the oil return in cooling is over, low pressure switch will be
shielded.
In addition, the system will control low pressure through the evaporator temp. TE to realize the low pressure
protection function.
In cooling, confirm through Tc2AVE:
Keep for 5 seconds, stop to alarm, after 3-minute standby, the
unit can restartup. In 60 minutes it occurs 3 times continously,
unit will stop to alarm and the failure can be resumed after being
electrified again.
Reduce FQY rapidly 2HZ/S
Reduce FQY rapidly 1HZ/S
Reduce FQY slowly 1HZ/10S
Remain FQY
Increase FQY slowly 1HZ/10S
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