Fujitsu AIRSTAGE V-II, Service Manual

Page: 34 / 230

02-11
2-5-3 Defrost Operation Control
< Defrosting start condition >
Accumulated heating operation time is 40 minutes or longer
[Accumulated heating operation time is reset at the end of cooling operation or defrosting operation.]
and
an outdoor unit satisfies condition or below
Condition : "Heat exchange temperature -2°C" accumulated operating time is 180 minutes or longer
(75 minutes for indoor unit connection capacity 90% at 1 outdoor unit connection)
Condition : After the following all condition satisfied, "heat exchange temperature defrosting start judgment
temperature and during heat exchange liquid temperature drop" accumulated time:10minutes
(a) accumulated heating operation time 30 minutes
(b) 10 minutes have elapsed after outdoor unit starting
(c) 5 minutes have elapsed since oil recovery
* Defrosting start and end judgment temperature are determined by the outdoor temperature.
Defrosting start judgment temperature = 0.8 x outdoor temperature - 11.6 (However, -27.6°C to
- 6°C)
< Defrosting end condition >
At all outdoor units, heat exchange liquid temperature end judgment temperature
or
when 10 minutes have elapsed from the start
(When the indoor unit connection capacity is 90% or less, after 15 minutes have elapsed.)
Defrosting end judgment temperature = 0.39 x outdoor tempe 12.7 (However, 5 to 12°C range)
If the calculated result is lower tha
n -27.6 , the judgment temperature is defined as -27.6
If the calculated result is higher tha
n -6 , the judgment temperature is defined as -6
2-5-2 Pre-heat Operation
This pre-heat operation protects the start up failure by preventing the refrigerant from soaking into the oil in compressor.
Crankcase heater ON: 30 minutes elapsed since installed compressors stopped (However, ON when power turned on)
*It doesn't control according to the temperature.
Inverter use: Decided by INV compressor ON-OFF
Constant speed use: Decided by constant speed compressor ON-OFF
If the calculated result is lower tha
n 5 , the judgment temperature is defined as 5
If the calculated result is higher tha
n 12 , the judgment temperature is defined as 12
OFF: Installed compressors operation