Service Manual

SiUS091133 Control Specification

Function and Control 48

3.6 Freeze-up Protection Control

Outline During cooling operation, the signal sent from the indoor unit controls the operating frequency

limitation and prevents freezing of the indoor heat exchanger. (The signal from the indoor unit is

divided into zones.)

Detail The operating frequency limitation is judged with the indoor heat exchanger temperature.

3.7 Heating Peak-cut Control

Outline During heating operation, the indoor heat exchanger temperature determines the frequency upper

limit to prevent abnormal high pressure.

Detail

ABC

FTXS09/12LVJU 9.5°C (49.1°F) 7.5°C (45.5°F) 5.5°C (41.9°F)

FTXS15/18/24/30/36LVJU, FDXS series 7°C (44.6°F) 5°C (41°F) 3°C (37.4°F)

(R16967)

Reset zone

Indoor heat exchanger

thermistor temperature

Up zone

Keep zone

Dropping zone

Stop zone

0˚C

(32˚F)

13˚C

(55.4˚F)

Zone Control

Stop zone When the temperature reaches the stop zone, the compressor stops.

Dropping zone The upper limit of frequency decreases.

Keep zone The upper limit of frequency is kept.

Up zone The upper limit of frequency increases.

Reset zone The upper limit of frequency is canceled.

ABCDE

09 class 60°C (140°F) 56°C (132.8°F) 53°C (127.4°F) 51°C (123.8°F) 46°C (114.8°F)

12 class 60°C (140°F) 52°C (125.6°F) 50°C (122°F) 48°C (118.4°F) 43°C (109.4°F)

15/18 class 60°C (140°F) 57°C (134.6°F) 56°C (132.8°F) 54°C (129.2°F) 52°C (125.6°F)

24/30/36 class 65°C (149°F) 56°C (132.8°F) 55°C (131°F) 53°C (127.4°F) 51°C (123.8°F)