Fujitsu AOTG30KMTC, Service Manual, Page: 158 / 199

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.
• When 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.
• When the discharge temperature becomes lower than the release condition, control of compressor
frequency is released.
• When the discharge temperature becomes higher than the compressor protection temperature,
the compressor is stopped and the indoor unit LED starts blinking.
Trigger condition 104°C
Compressor frequency
30 model -20 rps/120 seconds
34 model -14 rps/120 seconds
Release condition 101°C
Compressor protection temperature 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.
When the indoor unit heat exchanger temperature reaches release condition, the anti-freezing con-
trol is stopped.
Trigger condition 4°C
Release condition
Outdoor temp. ≥ 10°C*
1
Outdoor temp. ≥ 12°C*
2
7°C
Outdoor temp. < 10°C*
1
Outdoor temp. < 12°C*
2
13°C
*1: During the outdoor temperature dropping
*2: During the outdoor temperature rising
8-3. Current release control
The compressor frequency is controlled so that the outdoor unit input current does not exceeds cur-
rent limit value set according to the outdoor temperature.
The compressor frequency returns according to the operation mode, when the current becomes low-
er than the release value.
¢
Model: AOTG30KMTC
Operation mode Outdoor temp. (Ta) Trigger condition Release condition
Cooling
50°C ≤ Ta 7.5 A 7.0 A
46°C ≤ Ta < 50°C 10.0 A 9.5 A
40°C ≤ Ta < 46°C 12.5 A 12.0 A
Ta < 40°C 14.5 A 14.0 A
Heating
17°C ≤ Ta 10.0 A 9.5 A
12°C ≤ Ta < 17°C 11.5 A 11.0 A
Ta < 12°C 14.5 A 14.0 A
8-1. Discharge gas temperature over-rise prevention control
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8. Various protections
CONTROL AND FUNCTIONS CONTROL AND FUNCTIONS