Mitsubishi Heavy Industries V Multi FDC71VNX Technical Manual page 128

(5) Defrost operation
(a) Starting conditions
If all of the following defrost conditions A or conditions
B are satisfied, the defrost operation starts.
(i) Defrost conditions A
1) Cumulative compressor operation time after the
end of defrost operation has elapsed 37 [45]
minutes, and the cumulative compressor operation
time after the start of heating operation (remote
control ON) has elapsed 30 minutes.
2) After 5 minutes from the compressor ON
3) After 5 minutes from the start of outdoor fan
4) After satisfying all above conditions, if temperatures of
the outdoor heat exchanger temperature thermistor
(Tho-R1, R2) and the outdoor air temperature
thermistor (Tho-A) become lower than the defrost
operation starting temperature as shown by the right
figure for 15 seconds continuously, or the suction
gas saturation temperature (SST) and the outdoor
air temperature (Tho-A), which are obtained from
the value detected by the low pressure sensor (LPT)
stay for 3 minutes within the range below the defrost
operation start temperature as shown by the right
figure.However, it excludes for 10 minutes after the
startof compressor and the outdoor air temperature
is as shown by the lower figure.
LPT detection
2
Outdoor air temperature (°C)
Note (1) Figures in [ ] is for model FDC71.
(ii) Defrost conditions B
1) When previous defrost ending condition is the time
out of defrost operation and it is in the heating
operation after the cumulative compressor operation
time after the end of defrost operation has become
30 minutes.
2) After 5 minutes from the start of compressor
3) After 5 minutes from the start of outdoor fan
(b) Ending conditions
When any of the following conditions is satisfied, the
heating operation starts.
(i) When it has elapsed 8 minutes and 20 seconds after
the start of defrost operation. (After 10 minutes and
20 seconds for model FDC71)
(ii) When the outdoor heat exchanger temperatures (Tho-R1, R2), whichever the lower, becomes 12°C (model FDC71: 16°C)
or higher for 10 seconds continuously.
Model FDC71-140
Model FDC71
LPT invalid
4
Model FDC100-140
127
- -
-2
-5
-6
-10
-15
-20
-25
-27
-30
-25 -20 -18 -15 -10
Outdoor air temperature (℃)［Tho-A］
-8
-10
-15
-20
-24
-25
-30
-31
-35
-25 -20 -18 -15 -10
Outdoor air temperature (℃)［Tho-A］
-8
-10
-15
-20
-24
-25
-28.6
-30
-18
-25 -20 -15 -10
Outdoor air temperature (℃)［Tho-A］
'19 • PAC-T-327
Defrost operation start
temperature zone
-5 0 5 6 10
Defrost operation start
temperature zone
-5 0 5 6 10
Defrost operation start
temperature zone
-5 0 5 6 10