Heating High Pressure Protection; Anomaly Detection Control By The High Pressure Switch (63H1); Low Pressure Control - Mitsubishi Heavy Industries FDT71VNXWVH Service Manual

(c) Heating high pressure protection
(i) Protective control
1) As the indoor heat exchanger temperature (Thi-R) exceeds the setting value, the compressor speed (frequency) is
controlled to suppress the rise of high pressure.
2) Control value A is updated to an optimum value automatically according to the operating conditions.
Reset
Indoor heat exchanger temperature (°C)
(ii) Anomalous stop control
Operation control function by the indoor unit control - See the heating overload protection, page 20.
(iii) Adaptation to existing piping, stop control
If the existing piping adaptation switch, SW5-1, is turned ON, the compressor stops to protect existing piping when
the indoor heat exchanger temperature (Thi-R) exceeds the setting value.
(d) Anomaly detection control by the high pressure switch (63H1)
(i) If the pressure rises and operates the high pressure switch (opens at 4.15MPa/closes at 3.15MPa), the compressor stops.
(ii) Under any of the following conditions, E40 is displayed and it enters the anomalous stop mode.
1) When it occurs 5 times within 60 minutes that pressure rises and the compressor is stopped by 63H1.
2) When 63H1 has been in the open state for 30 minutes continuously, including the stop of compressor.
(e) Low pressure control
(i) Protective control
If the value detected by the low pressure sensor (LPT) exceeds the setting value, the compressor speed (frequency) is
controlled to restrain the drop of pressure.
(ii) Anomalous stop control
1) When a value detected by the low pressure sensor (LPT) satisfies any of the following conditions, the compressor
stops to run for its protection.
a) When the low pressure drops to 0.079MPa or under for 15 seconds continuously.
b) At 10 minutes after the start of compressor, the suction overheat becomes 30°C and the low pressure becomes
0.15MPa or under for 60 seconds continuously.
2) E49 is displayed under any of the following conditions and it enters the anomalous stop mode.
a) When the low pressure drops 5 times within 60 minutes and the compressor stops under any of the above conditions.
b) When a value detected with the low pressure sensor becomes 0.079MPa or under for 5 minutes, including the
stop of compressor.
3) However, when the control condition 1). a) is established during the compressor protection start III, E49 is
displayed at initial stop and it enters the anomalous stop mode.
Reduces compressor frequency
at every 30 seconds.
A
Reset
47
Indoor heat exchanger temperature (°C)
Reduces compressor frequency
at every 30 seconds.
0.150
Low pressure (MPa)
-
Model
FDC71
Note (1) Adaptation to existing piping is at ON.
Compressor stop
56
Retention
Reset
0.189
46
-
'19 • PAC-SM-332
Existing piping adaptation switch: SW5-1
OFF (Shipping) ON
Control value A (°C)
48-54 45-51