Mitsubishi Heavy Industries SRK100VNXWZRF Service Manual page 22

(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) Accumulative compressor operation time after the
end of defrost operation has elapsed 37 minutes, and
the accumulative 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 sensor
(Tho-R1, R2) and the outdoor air temperature
sensor (Tho-A) become lower than the defrost
operation start 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 (PSL)
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
start of compressor and the outdoor air temperature
is as shown by the lower figure.
PSL detection
Outdoor air temperature (°C)
(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 accumulative 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 13 minutes and 20 seconds after the start of defrost operation
(ii) When the outdoor heat exchanger temperatures (Tho-R1, R2), whichever the lower, becomes 12°C or higher for 60
seconds continuously
PSL invalid
2 4
Model FDC100
-2
-5
-6
-10
-15
-20
-25
-27
-30
-25 -20 -18
Model FDC100
-8
-10
-15
-20
-24
-25
-28.6
-30
-25 -20 -18
21
- -
'22 • PAC-SM-422
Defrost operation start
temperature zone
-15 -10 -5 0
Outdoor air temperature (℃)［Tho-A］
Defrost operation start
temperature zone
-15 -10 -5 0
Outdoor air temperature (℃)［Tho-A］
5 6 10
5 6 10