Panasonic U-4LE1E5 Service Manual page 17

3. Special Controls
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:
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 minutes." 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 1 minute
operation stop
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.
–21.4
Reverse cycle defrost
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.
1 - 11
Heat exchange liquid temperature °C
Defrosting operation
end temperature
6
10
–1
–3
–8
–10
The frost detection area is
located under the thick lines
–23
–25
1 minute
stop
Mini VRF SYSTEM
Mini VRF SYSTEM
Control Functions
Control Functions
(The end temperature is
different from the above
detection temperature.)
External temperature °C
L1
L2
Fig. 1-4
Normal
operation
1