Panasonic U-10MF1E8 Service Manual page 18

4. Special Controls
4-2-3. Flow of system refrigerant oil recovery control
(1) Simplified flow of system refrigerant oil recovery control
System refrigerant oil recovery control follows this flow:
Normal operation
minutes) 3-minute stop
(2) Cooling cycle
1
Control time
Outdoor units
Electronic control valve Valves at all indoor units operate at a fixed pulse according to the indoor unit capacity.
Indoor RAP valve kit
units
(3) Heating cycle
Control time
Outdoor units
Electronic control valve Valves at all indoor units operate at 480 pulses.
Indoor RAP valve kit
units
4-3. Defrost Control
4-3-1. Defrost control method
This system uses the following 2 defrost methods.
(1) If there is 1 outdoor unit in the refrigerant system: Reverse cycle defrost
(2) If there are 2 or more outdoor units in the refrigerant system: Outdoor unit cycle defrost
4-3-2. Constraint conditions
(1) Frost detection does not occur for 5 minutes after operation starts.
(2) Defrost does not begin again for 35 minutes of A/C operation after defrost was once completed.
(3) If all indoor units are stopped while defrost control is in effect, 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.
4-3-3. 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
3-minute stop (May stop for 6 minutes.)
Normal operation
Maximum 3 minutes (Stops once before and once after control.)
All outdoor units operate at maximum horsepower.
Valve kits at all indoor units operate in Cooling mode (OFF status.)
Fan operates at the set fan speed, stops, or operates at L speed, depending on the
Fan
indoor unit operation mode.
Maximum 3 minutes (Stops once before and once after control.)
All outdoor units operate at maximum horsepower.
Valve kits at all indoor units operate in Heating mode (ON status).
Fan operates at the set fan speed, stops, or operates at L speed, depending on the
Fan
indoor unit operation mode.
Heat exchange liquid temperature °C
Defrosting operation
end temperature
6
–1
–3
–8
–10
–23
–25
System refrigerant oil recovery control (Max. 3
(The end temperature is different from the
above detection temperature.)
10
External temperature °C
L1
L2
The frost detection area is
located under the thick lines
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3-WAY SYSTEM
Control Functions