Outdoor Unit Protection Control; Cooling Oil Return Control; Heating Oil Return Control; Overload Control - Panasonic S-22KA1E5 Service Manual

14. Outdoor Unit Protection Control

14.1 Cooling Oil Return Control

•
Oil Return control will operate 1 cycle for every 3 hours of compressor accumulation run times (normal cooling
operation mode continuously).
•
Cooling oil return control will take 5 minutes to complete.
•
During the control, Outdoor unit is fixed in cooling refrigerant cycle operation with fixed compressor frequency
and all indoor's expansion valves are fixed open (even the indoor is in OFF operation or thermo OFF).
•
Compressor accumulation run time counter will be reset when below conditions happened :
Completion of cooling oil return control.
o
System operation mode changed.
o

14.2 Heating Oil Return Control

•
This control will operate 1 cycle if either 1 of below conditions fulfilled:
Every 3 hours of compressor accumulation run times (normal heating operation mode continuously).
o
Max Heat Exchanger Temperature (thermo ON) – Min Heat Exchanger Temperature (thermo OFF) > 15°C
o
for 3 minutes continuously.
•
During the control, Outdoor unit is continued in heating refrigerant cycle operation and expansion valve for indoor
units (thermo OFF / stand-by) will be fully opened (for one minute) one at a time sequentially started from indoor
unit with lowest Heat Exchanger Temperature (thermo OFF).
•
Compressor accumulation run time counter will be reset when below conditions happened :
Completion of heating oil return control.
o
All indoor units thermo ON at 3rd hour of accumulation.
o
System operation mode changed.
o
Deice control activated.
o

14.3 Overload Control

•
Overload control will operate if either 1 of below conditions happened :
During Cool Mode
o
Outdoor heat exchanger temp > +58°C for 10 seconds.
During Heat Mode
o
Outdoor heat exchanger temp < -30°C when outdoor ambient > -5°C
Outdoor heat exchanger temp < -35°C when outdoor ambient ≤ -5°C
•
Every interval of 30sec, compressor frequency will reduce 10% if the outdoor heat exchanger temperature still at
down zone.
Cooling Operation Cooling Operation
Unchanged Unchanged
Free Free
zone zone
zone zone
o o
o o
54 54 C C
56 56 C C
•
The compressor frequency will only reduce max 3 times OR to minimum frequency.
•
For Heat operation, If compressor already reduced to minimum level but temp still at down zone, gas bypass
valve will opens.

14.4 Low Load Control

•
Low Load control will operate if either 1 of below conditions happened :
Indoor heat exchanger temp < 0°C during cooling operation.
o
Indoor heat exchanger temp > 54°C for 5 seconds during heating operation.
o
•
Every interval (15 seconds for cool mode; 30 seconds for heat mode), compressor frequency will reduce 10% if
the indoor heat exchanger temp still at down zone.
•
The compressor frequency will only reduce to minimum frequency.
•
If compressor already reduced to minimum level but temp still at down zone, gas bypass valve will opens.
Heating (Outdoor >- 5 Heating (Outdoor >- 5
Down Down
Down Down
zone zone
zone zone
o o
58 58 C C
o o
-30 -30 C C
Cooling Operation Cooling Operation
Down Down Unchanged Unchanged
zone zone zone zone
o o
o o
0 0 C C
3 3 C C
o o
C) C)
Unchanged Unchanged Free Free
zone zone zone zone
o o
-25 -25 C C
Free Free
Free Free
zone zone
zone zone
o o
5 5 C C
216
o o
≤ ≤
Heating (Outdoor Heating (Outdoor - 5 - 5
Down Down Unchanged Unchanged Free Free
zone zone zone zone zone zone
o o
o o
-35 -35 C C
-30 -30 C C
Heating Operation Heating Operation
Down Down
zone zone
o o
o o
52 52 C C
54 54 C C
C) C)