Fujitsu ASU18RLB Service Instructions Manual page 23

3. ANTIFREEZING CONTROL (Cooling and Dry mode)
The compressor frequency is decrease on cooling & dry mode when the indoor heat exchanger
temperature sensor detects the temperature lower than Temperature .
Then, the anti-freezing control is released when it becomes higher than Temperature .
( Table 24 : Anti-freezing protection operation / Release temperature )
Outdoor temperature
Over than 50°F (10°C)
or 54°F (12°C)
Less than 50°F (10°C)
or 54°F (12°C)
*1. When the temperature drops.
*2. When the temperature rises.
4. COOLING PRESSURE OVERRISE PROTECTION
When the outdoor unit heat exchange sensor temperature rises to 152.6°F(67°C) or greater,
the compressor and the outdoor fan motor are stopped and trouble display is performed.
5. HIGH TEMPERATURE RELEASE CONTROL (Heating mode)
On heating mode, the compressor frequency is controlled as following based on the
detection value of the indoor heat exchanger temperature sensor.
[ Control System ]
Indoor heat exchange
temperature rises
145.4°F
(63°C)
The compressor frequency is
decreased 25rps every 120seconds.
131°F
(55°C)
The compressor frequency is
decreased 3rps every 60seconds.
127.4°F
(53°C)
It returns to the normal operation
Temperature Temperature
*1
*2 39.2°F
(4°C)
*1
*2
Compressor is stopped
Stable zone
Indoor heat exchange
temperature drops
44.6°F
(7°C)
55.4°F
(13°C)
122°F
(50°C)
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