Panasonic U-4LE1E5 Service Manual page 16

3. Special Controls
3-4-3. Frost detection
(a) Frost is not detected at the outdoor unit heat exchanger for 5 minutes after operation starts.
(b) Frost is detected when either Condition 1 or 2 below is met.
Condition 1:
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.
Condition 3:
Regardless of this figure, the defrosting
will be made even if the liquid temperature
lower than -3°C for 90 minutes continuously.
It is also possible to avoid this
performance. If you adjust the desired
setting, follow the steps below.
-3°C EEPROM "CA" -3, -6 ~ -30
"CA" becomes ineffective.
The setting of "-3°C" can be
changed to "-6 ~ -30°C" .
90 mins. EEPROM "A7" 0 ~ 120 minutes.
In case of "FF" setting, the
setting becomes ineffective.
The setting of "90 mins." can be
changed to "0 ~ 120 minutes".
3-4-4.Defrost mask time
The next defrost operation will not start until the defrost mask time (= 35 minutes) has elapsed following the
previous defrost operation.
* While defrost control is in effect, if all indoor units stop, or if the outdoor unit is restarted after it was stopped
for protective control or a similar reason, then defrost control may start again after a minimum of 10 minutes.
3-4-5.General flow of reverse cycle defrost
(1) General flow of reverse cycle defrost control
Reverse cycle defrost control follows this flow process:
Normal
operation
Control time
Outdoor units
Electronic
Indoor
control valve
units
Fan
3-4-6.Defrost end judgment conditions
Defrost ends when the below defrost end conditions are met.
Condition 1: Defrost end judgment occurs when the temperature at the temperature sensor installed on the
outdoor heat exchanger is 10°C or higher (or has been 6°C or higher continuously for 1 minute).
Condition 2: When the maximum defrost time shown in the table above has elapsed, defrost end judgment
occurs.
1 minute Reverse cycle defrost
stop control (Max. 12 minutes)
Max. 12 minutes (stops once before and after control)
Operates at a compressor frequency of 75 Hz. The outdoor fan stops.
All indoor units operate at a fixed pulse according to the indoor unit capacity.
The fan stops.
Heat exchange liquid temperature °C
6
–21.4
–1
–3
–8
1 minute
stop
1 - 10
Mini VRF SYSTEM
Control Functions
Defrosting operation (The end temperature is
end temperature different from the above
detection temperature.)
10 External temperature °C
L1
L2
–10
The frost detection area is
located under the thick lines
–23
–25
Fig. 1-4
Normal
operation