Defrost Control - Panasonic U-8ME1E8E Service Manual

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 5 minutes after operation starts.
- Defrost does not begin again for 35 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 10 minutes after restart occurs.
9-3. Frost detection
(A) Frost detection does not occur for 5 minutes after operation starts.
(B) 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.
–21.4
Defrost control method
Reverse cycle defrost
Outdoor unit cycle defrost
Heat exchange liquid temperature °C
Defrosting operation
end temperature
10
10
–1
–3
–8
–10
The frost detection area is
located under the thick lines
–23
–25
1 - 27
2WAY SYSTEM
Control Functions-Outdoor Unit
(The end temperature
is different from the
above detection
temperature.)
External temperature °C
L1
L2
1