Defrost Control - Panasonic U-8ME1E81 Service Manual

9. Defrost Control

9. Defrost Control
9-1. Defrost Methods
This system uses the following 2 defrosting systems.
System employs
1 outdoor unit in the refrigerant system
2 or more outdoor units in the refrigerant system
9-2. Constraint Conditions
Frost detection does not occur for 10 minutes after operation starts.
Defrost does not begin again for 40 minutes of operation after defrost was once completed.
If all indoor units are stopped while defrosting, or if the outdoor unit is stopped due to protection control or
another reason, then defrost control will not start for a minimum of 5 minutes after restart occurs.
Time until next defrost permission when defrost was completed is changed according to the ambient air temperature.
Ambient air
To ≤ -10°C
temperature
Minute XX + 6
9-3. Frost Detection
(1) Frost detection does not occur for 5 minutes after operation starts.
(2) Frost is detected when either condition 1 or 2 below is met.
Condition 1: L2 line or below is detected twice, each time continuously for 4 minutes, when the compressor
is operating.
Condition 2: L1 line or below is detected for a total of 60 minutes when the compressor is operating.
–25
-10 < To ≤ -5°C -5°C < To
XX + 3 XX
Heat exchange liquid temperature °C
10
–1
–3
–8
1 - 27
Control Functions-Outdoor Unit
Control Functions-Outdoor Unit
Defrost control method
Reverse cycle defrost
Outdoor unit cycle defrost
EEPROM setting in main outdoor unit
CODE: A3
Setting No.
20
21
40
41
90
(The end temperature
Defrosting operation
is different from the
end temperature
above detection
temperature.)
10 External temperature°C
L1
L2
–10
The frost detection area is
located under the thick lines
–25.5
–27.5
2WAY SYSTEM
2WAY SYSTEM
XX
20
21
Interval of "1"
40
(factory preset mode)
Never use
1