Various Protections; Discharge Gas Temperature Over-Rise Prevention Control; Anti-Freezing Control (Cooling And Dry Mode) - Fujitsu ACUH09LUAS1 Service Manual

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
Compressor frequency
Release condition
Compressor protection temperature

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
Release condition
*1: During the outdoor temperature dropping
*2: During the outdoor temperature rising
8-1. Discharge gas temperature over-rise prevention control
Outdoor temp. ≥ 50°F (10°C)*
Outdoor temp. ≥ 53.6°F (12°C)*
Outdoor temp. < 50°F (10°C)*
Outdoor temp. < 53.6°F (12°C)*
- (04-32) -
219.2°F (104°C)
-20 rps/120 seconds
213.8°F (101°C)
230.0°F (110°C)
1
2
1
2
39.2°F (4°C)
44.6°F (7°C)
55.4°F (13°C)
8. Various protections