Defrost Operation Control - Fujitsu AUXB04GALH Service Manual

2-6-3 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
One of Heat-Ex satisfies condition
Condition : Accumulated operating time is 150 minutes* or longer:
"Heat exchange liquid temperature (TH9 and TH10)
*75 minutes: when indoor unit connection capacity
Condition : Accumulated time 10 minutes:
"Heat exchange liquid temperature (TH9 and TH10)
"During heat exchange liquid temperature keeps droping "
-However, -27.6°C to - 6°C
If the calculated result is lower than -27.6°C, the judgment temperature is defined as -27.6°C
If the calculated result is higher than -6°C, the judgment temperature is defined as -6°C
(Defrosting start judgment temperature are determined by the outdoor temperature.)
: Less than 10 minutes operation at outdoor temperature below 2
Condition
< Defrosting end condition >
At all outdoor units, heat exchange liquid temperature
and all of outdoor unit's Suction temperature - Low pressure saturation temperature
or
When 15 minutes have elapsed from the start
Defrosting End Judgment Temperature(
*
-However, 5°C to 12°C range
If the calculated result is lower than 5°C, the judgment temperature is defined as 5°C.
If the calculated result is higher than 12°C, the judgment temperature is defined as 12°C
or or
And
*Defrosting Start Judgment Temperature(°C) = 0.8 x Outdoor temperature (°C) - 11.6
below
-2°C"
90% at 1 outdoor unit connection.
Defrosting End Judgment Temp.* and 180sec elapsed,
C)= 0.39 x outdoor temperature(
°
02-12
Defrosting Start Judgment Temperature*
occured 20 times.
5°C
) + 12.7
°C