Defrost Operation Control - Fujitsu AS* A09LEC Service Instruction

22. DEFROST OPERATION CONTROL

1. CONDITION OF STARTING THE DEFROST OPERATION
The defrost operation starts when the outdoor heat exchanger temperature sensor (Tn) detects
the temperature lower than the values shown in Table18.
( Table 18 : Condition of starting Defrost Operation )
1 time defrosting
ST
after starting operation
Defrosting after 2
ND
upon starting operation
Tn10 : Temperature of continuous operation at 10minutes.
Tnb : Back 5minutes temperature
Integrating defrost
(Constant monitoring)
*1 : If the compressor continuous operation time is less than 10 minutes, the OFF number of the compressor is counted.
If any defrost operated, the compressor OFF count is cleared.
2. CONDITION OF THE DEFROST OPERATION COMPLETION
Defrost operation is released when the conditions become as shown in Table19.
( Table19 : Defrost Release Condition )
Outdoor heat exchanger temperature sensor value is higher than
or
Compressor operation time has passed 15 minutes.
Compressor integrating operation time
Less than 20 min.
Does not operate
Compressor integrating operation time
time
Less than 35 min.
Does not operate
More than 240 min.
(For long continuous operation)
- 3°C
Release Condition
20 to 60 min. More than 60 min.
- 9°C
More than 35min.
Tn-Tn10 < - 5deg
Tn-Tnb < - 2deg
However, Tn < - 6°C
=
Compressor integrating operation time
More than 213 min.
(For long continuous operation)
- 5°C
+16°C
01-16
- 5°C
Less than 10min.*1
(For intermittent operation)
OFF count of the compressor
40 times.