Specifications

SiUS12-928_A Control Specification
Function and Control 52
3.10 Defrost Control
Outline Defrosting is carried out by the cooling cycle (reverse cycle). The defrosting time or outdoor heat
exchanger temperature must be more than a certain value to finish.
Detail Conditions for Starting Defrost
 The starting conditions are determined with the outdoor temperature and the outdoor heat
exchanger temperature.
 The system is in heating operation.
 The compressor operates for 6 minutes.
 More than minutes of accumulated time pass since the start of the operation, or ending the
previous defrosting.
Conditions for Canceling Defrost
The target heat exchanger canceling condition temperature is selected in the range of 4 ~ 12°C (39
~ 54°F) according to the outdoor temperature.
The defrost operation operates120 seconds after the start. (A → B)
Then the defrost operation stops at the following conditions.
1. When the heat exchanger temperature reaches the target heat exchanger temperature. (B → C)
2. When 650 seconds have passed after the start even if the heat exchanger temperature does not
reach the target heat exchanger temperature. (C)
18 class 24/32 class
(minutes) 43 38
(Hz) 54 39
(Hz) 82 62
(seconds) 120 60
(pulse) 450 350
(pulse) 450 400
(pulse) 140 160
Frequency
Compressor
Four-way valve
Fan
Electronic expansion
valve opening
(operating room)
Electronic expansion
valve opening
(stop room)
ON
AB C
OFF
ON
OFF
ON
OFF
0 Hz
Hz
5 sec.
450 pulse
0 pulse
PI control
5 sec.
60 sec.
650 sec.
120 sec.
Initial opening
Initial opening
(R12296)
Hz
sec.
pulse
pulse
pulse