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Entering condition:
When the unit has run in heating mode for 33 minutes and the compressor has run for 50 minutes accumulatively since
the last defrosting. By measuring the defrosting sensor Tdef1 or Tdef2 and outdoor ambient temp. sensor TA
，
any
outdoor can meet the below conditions for 5 minutes, this outdoor will enter defrosting operation.
a. When Tdef1 or Tdef2<= -6
℃
for 5 minutes;
b. When -6<Tao<5, -13.6<Tdef1 or Tdef2<-6 for 5 minutes, enter defrosting;
c. Tao<-6, Tdef1 or Tdef2<= -15 for 5 minutes, and compressor has run for 90 minutes between the two defrosting;
In defrosting operation
a.4-way valve OFF
b.Outdoor motor OFF
c.Anti-cold air control of indoor motor OFF
d.Outdoor LEVa1,2 OFF
e.In cooling mode or fan mode, fan motor keep original.
Quit defrosting
Any of the below conditions can be met, the outdoor unit in defrosting will quit defrosting.
a. After defrosting begins, 10 minutes later, defrosting is over;
b.Detect the defrosting condition of outdoor heat exchanger by Tdef1 or Tdef2, all the temperatures at the defrosting
point are over 10
℃
for 60 seconds or reaches 15
℃
or 10 seconds, quit defrosting;
c.High pressure Pd is over 35kgf/cm2, quit defrosting.
17.5 Oil return operation control
1.Entering condition
When outdoor total running capacity is over 25% and less than 75% for 4 hours, or outdoor total running capacity is
less than 25% for 2 hours, the system will enter oil return operation.
*When outdoor total running capacity is over 75% for 10 minutes continuously, the oil return time will be cleared.
*In defrosting operation, when outdoor total running capacity is over 75% for 5 minutes continuously, the oil return
time will be cleared.
2.Oil return procedure:
All outdoors start up, and run with 75% of total capacity in cooling mode; In oil return course, outdoor leva1, 2 open to
250pls;
In oil return course, the valve box connecting with indoor units in heating &thermo on and in heating &thermo off
changes into cooling mode. All THERMO ON, indoor valves 250pls, All THERMO OFF, indoor valves 125pls; During oil
return course
，
indoor fan motor in thermo on mode keeps original .when Tdi or Toil is over 105
℃
, indoor LEV will
open larger 10%.
In oil return, Levb is OFF.
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