Service Manual

Table Of Contents
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 40 min. More than 40 min.
Condition Does not operate
Tn-Tn10 < -5 deg (Tn ≤ -6°C)
Tn-Tnb < -2 deg (Tn ≤ -6°C)
Tn ≤ -20°C (Ta ≥ -10°C)
Tn ≤ -7°C or Tn ≤ -25°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)
13°C or more
Compressor operation time 15 minutes
- (04-23) - 6. Defrost operation control
CONTROL AND
FUNCTIONS
CONTROL AND
FUNCTIONS