Panasonic U-8MF2E8 Service Manual page 41

9. Defrost Control
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
9-4. Reverse Cycle Defrost
Reverse cycle defrost is performed in systems where only 1 outdoor unit is connected to the refrigerant system.
Special control : Reverse Cycle Defrost features one of the functions of special control.
9-4-1. Start of Reverse Cycle Defrost
When conditions of section "9-2" and "9-3" contents are satisfied, defrost control is started.
9-4-2. Simplified Flow of Reverse Cycle Defrost
Whole process
Reverse cycle defrost shall be performed as the flow mentioned below.
(0) Normal operation
(1) Pre-processing time of reverse cycle defrost for 2.5 minutes
(2) Reverse cycle defrost processing time *
(3) Post-processing time of reverse cycle defrost for 2 minutes
(4) Normal operation
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
–25.5
–27.5
1
1 - 33
3WAY SYSTEM
Control Functions
(The end temperature
is different from the
above detection
temperature.)
External temperature°C
L1
L2
1