Panasonic R410A Service Manual page 15

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.
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
control valve
Indoor
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 50°F or higher (or has been 42.8°F or higher continuously for 1 minute).
Condition 2: When the maximum defrost time shown in the table above has elapsed, defrost end judgment
occurs.
–6.5
Reverse cycle defrost
control (Max. 12-minute)
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 - 9
Heat exchange liquid temperature °F
Defrosting operation
end temperature
42.8
50
30
26
17
14
The frost detection area is
located under the thick lines
–9
–13
Fig. 1-4
1-minute
stop operation
Mini VRF SYSTEM
Control Functions
(The end temperature is
different from the above
detection temperature.)
External temperature °F
L1
L2
Normal
1
2
3
4
5
6