Air Conditioner Service Manual
7
(5) Defrost
Defrosting of the outdoor heat exchange is controlled by the microprocessor with detection by the indoor
pipe temperature sensor.
Defrost control type is according to the JC on the PCB whether is connected.
z When the JC is connect on the PCB
When one of the conditions of A, Band C is satisfy, the defrosting operation stars.
A. IPT--- indoor pipe temperature
In the condition A, it must satisfy the conditions a), b)and c) then into defrosting operation.
a) IPT1 satisfy IPT1=IPT
MAX
－△IPT（8℃）
b) t5≥50minutes(the compressor cumulative operation time≥50 minutes, t5 is permitted move
and lower than t1 too).
c)
IPT＜40℃，and keep 2 minutes.
According to the condition A enter the defrosting operation, the first defrosting operation time is
8minutes; After defrosting operation one cycle, and then judge and regulate the defrosting operation
time.
B. After the compressor cumulative operation time exceeds 120 minutes and the temperature of the IPT
is less then 35
℃ for 2 minutes. When the defrosting operation time on this condition exceeds
8minutes, it will terminate.
C. After the compressor operation continuously for 20 minutes and the IPT is less than 23℃ or from
the last time of defrosting operation is 50 minutes or more interval. When the defrosting operation
time on this condition exceeds 10 minutes, it will terminal.
z When the JC isn’t connected on the PCB
When the conditions of a) or b) is satisfy, the defrosting operation starts.
a) Have the outdoor sensor on the outdoor unit: Under the heating operation, the compressor cumulative
operation time exceeds 50 minutes and the temperature of the outdoor pipe temperature sensor reads
lower than －4
℃.
b) No the outdoor on the outdoor unit: Under the heating operation, the compressor cumulative
operation time exceeds 50 minutes, if the indoor pipe temperature sensor reads lower than 40
℃
continuously for 2minutes.
z Defrost terminating conditions
When the condition c) or d) is satisfy, the defrosting operation will terminal.
c) The outdoor defrost sensor reads 15
℃ or more.
d) The defrosting time exceeds 10 minutes.
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