Fujitsu ACUH09LUAS1, Service Manual

Page: 138 / 153

8. Various protections
8-1. Discharge gas temperature over-rise prevention control
The discharge gas temperature sensor (discharge thermistor: outdoor unit side) detects the dis-
charge gas temperature.
• →hen the discharge temperature becomes higher than the trigger condition, the compressor fre-
quency is decreased as the table below, and it continues to decrease until the discharge tempera-
ture becomes lower than the trigger condition.
• →hen the discharge temperature becomes lower than the release condition, control of compressor
frequency is released.
• →hen the discharge temperature becomes higher than the compressor protection temperature,
the compressor is stopped and the indoor unit LED starts blinking.
Trigger condition 219.2°F (104°C)
Compressor frequency -20 rps/120 seconds
Release condition 213.8°F (101°C)
Compressor protection temperature 230.0°F (110°C)
8-2. Anti-freezing control (cooling and dry mode)
The compressor frequency is decrease in cooling and dry mode when the indoor unit heat exchang-
er temperature sensor detects the temperature lower than the trigger condition.
→hen the indoor unit heat exchanger temperature reaches release condition, the anti-freezing con-
trol is stopped.
Trigger condition 39.2°F (4°C)
Release condition
Outdoor temp. ≥ 50°F (10°C)*
1
Outdoor temp. ≥ 53.6°F (12°C)*
2
44.6°F (7°C)
Outdoor temp. < 50°F (10°C)*
1
Outdoor temp. < 53.6°F (12°C)*
2
55.4°F (13°C)
*1: During the outdoor temperature dropping
*2: During the outdoor temperature rising
8-1. Discharge gas temperature over-rise prevention control
- (04-32) -
8. Various protections
C
O
N
TR
O
L
A
N
D
FU
N
C
TI
O
N
S
C
O
N
TR
O
L
A
N
D
FU
N
C
TI
O
N
S