Mitsubishi Heavy Industries FDU Series Service Manual page 42

(ii) Heating
1) Operating conditions
When the outdoor air temperature (TH2) is 13ºC or higher continues for 30 seconds while the compressor speed is other
than 0 rps.
2) Detail of operation
After the outdoor fan operates at -3 speed for 60 seconds; the corresponding outdoor heat exchanger temperature shall im-
plement the following controls.
Outdoor heat exchanger temperature = < 10ºC
a)
After the outdoor fan speed rises (up) to 1 speed for 60 seconds; if the outdoor heat exchanger temper-
ature is lower than 10ºC, gradually increase the outdoor fan speed by 1 speed.
10ºC < Outdoor heat exchanger temperature = < 13ºC
b)
After the outdoor fan speed maintains for 20 seconds; if the outdoor heat exchanger temperature is
10ºC - 13ºC, maintain outdoor fan speed again.
c) Outdoor heat exchanger tempeature > 13ºC
After the outdoor fan speed drops (down) to 1 speed for 60 seconds; if the outdoor heat exchanger temper-
ature is higher than 38ºC, gradually reduce outdoor fan speed by 1 speed. (Lower limit 2nd speed)
3) Reset conditions
When either of the following conditions is satisfied.
a) The outdoor air temperature (TH2) is 11ºC or lower.
b) The compressor speed is 0 rps.
(f) Outdoor fan motor protection
If the outdoor fan motor has operated at 75 min
(4) Defrost operation
(a) Starting conditions (Defrost operation can be started only when all of the following conditions are satisfied.)
(i) After start of heating operation.
When it elapsed 35 minutes. (Accumulated compressor operation time)
(ii) After end of defrost operation.
When it elapsed 35 minutes. (Accumulated compressor operation time)
(iii) Outdoor heat exchanger sensor (TH1) temperature.
When the temperature has been below － 5ºC for 3 minutes continuously.
(iv) The difference between the outdoor air sensor temperature and the outdoor heat exchanger sensor temperature (TH2-TH1)
● The outdoor air temperature ≧ － 2ºC : 7ºC or higher
● － 15ºC ＜ The outdoor air temperature ＜ － 2ºC : 4/15 × The outdoor air temperature + 7ºC or higher
● The outdoor air temperature ≦ － 15ºC : － 5ºC or higher
(v) During continuous compressor operation.
In addition, when the speed command from the indoor control of the indoor unit during heating operation
has counted 0 rps 10 times or more and all conditions of (i), (ii) above and the outdoor air temperature is 3ºC
or less and the temperature for outdoor heat exchanger sensor (TH1) is － 5ºC or less: 62 rps or more, － 4ºC
or less: less than 62 rps are satisfied, defrost operation is started.
or lower for more than 30 seconds, the compressor and fan motor are stopped.
-1
0
-5
-10
-15
-20
-20 -15 -10 -5
Outdoor air temperature (℃)
41
- -
'19 • PAC-SM-334
Defrost operation
start
0 5 10