42 SERVICE MANUAL FOR AMERICA
outdoor FM
reverse valve
20s 30s 30s
figure 5
七．
Defrost of heating mode(
figure 6)
1.
Defrost start condition
If outdoor ambient is more than or equal to 61
O
F,it can’t defrost. When the time of defrost
interval is end , outdoor coil pipe temp. and outdoor ambient temp. continuous meet
all conditions for 5 minutes, it enter defrost process:
1)
If outdoor ambient temp. less than or equal to
32
O
F，when T
盘
≤0.8T
环
+a
O
F（a is a adjust
constant）, it enter defrost process.
2)
If outdoor ambient temp. more than 32
O
F and less than or equal to 59
O
F，when T
盘
≤ 0.2 T
环
+a
O
F, it enter defrost process.
3)
If outdoor temp. sensor is failure, when outdoor coil temp.
T
盘
≤+a
O
F, it enter defrost
process.
4)
If coil temp. sensor of outdoor unit is failure, when defrost interval time is end, it enter defrost, the
time of defrost is four minutes.
5)
During the first ten minutes of outdoor running in heating mode, the time is clear and it judge
whether outdoor coil pipe temp. and outdoor ambient temp. satisfy defrost condition, if the
frequency of compressor is 25HZ and satisfy defrost condition, then if enter defrost process. After
end defrost process or over 10 minutes it return normal running.
2.
Defrost end condition
1)
T
盘
≥b
O
F（b is a adjust constant）or defrost time more than or equal to c minutes
（c is a adjust constant），it exit defrost process.
2)
When outdoor coil pipe sensor is failure, defrost time is four minutes, it exit defrost process after
four minutes.
3.
Interval time of defrost
1)
Defrost interval time restriction: Max 120 minutes, Min 25 minutes.
2)
The first frost interval time is 0 minute after heating.
3)
The second defrost interval time is base on 60 minutes, it adjust according to below table.
4)
Form second time, defrost interval time adjustment as below table.
Interval time（Td）
change
Td ＜２ minutes
Last interval time add 5
minutes
3 minutes≥Td≥2
minutes
Same as last interval time
≥４ minutes
Last interval time reduce 5
minutes
4.
Time sequence of defrost process(figure 6).
