Fujitsu ROG07KPCA, Service Manual

Page: 113 / 130

6. Defrost operation control
Tn: Outdoor unit heat exchanger temperature
Ta: Outdoor temperature
Tn10: Temperature at 10 minutes after compressor start
Tnb: Temperature before 5 minutes
•
Triggering condition
The defrost operation starts when outdoor unit heat exchanger temperature sensor detects the
temperature lower than the values shown below.
– 1st time defrosting after starting operation
Compressor integrating
operation time
Less than 17 min. 17 to 57 min. More than 57 min.
Condition Does not operate
Tn ≤ -9°C and Tn-Ta ≥ 5
deg
Tn ≤ -5°C
– 2nd time and after
Compressor integrating
operation time
Less than 25 min. More than 25 min.
Condition Does not operate
Tn-Tn10 < -5 deg (Tn ≤ -6°C)
Tn-Tnb < -2 deg (Tn ≤ -6°C)
Tn ≤ -17°C (Ta ≥ -10°C)
Tn ≤ Ta-7°C or Tn ≤ -20°C (Ta < -10°C)
– Integrating defrost (Constant monitoring)
Compressor integrating
operation time
More than 240 min. (For
long continuous
operation)
More than 213 min. (For
long continuous
operation
Less than 10 min.* (For
intermittent operation)
Condition Tn ≤ -3°C Tn ≤ -5°C
Count of the compressor
off: 40 times
*: If the compressor continuous operation time is less than 10 minutes, the number of the com-
pressor off is counted. If any defrost operated, the compressor off count is cleared.
•
Release condition
The defrost operation is released when either one of the conditions below is satisfied.
Outdoor unit heat exchanger temperature
(after 1 minute or later since compressor start)
16°C or more
Compressor operation time 15 minutes
- (04-21) -
6. Defrost operation control
CONTROL AND FUNCTIONS CONTROL AND FUNCTIONS