SiUS04-924_A Control Specification
36 Function and Control
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 A minutes of accumulated time pass since the start of the operation, or ending the
previous defrosting.
Conditions for Canceling Defrost
The judgment is made with outdoor heat exchanger temperature. (4 ~ 18°C, 39.2 ~ 64.4°F)
A (minutes) 38
B (Hz) 39
C (Hz) 62
D (seconds) 60
E (seconds) 120
F (seconds) 650
G (seconds) 60
H (pulse) 450
J (pulse) 350
K (pulse) 400
Frequency
Compressor
Four way valve
Fan
ON
OFF
ON
OFF
ON
OFF
0Hz
B Hz
C Hz
5 sec.
J pulse
K pulseH pulse
Initial opening
PI control
5 sec.
G sec.
(R13533)
Electronic expansion
valve opening
D sec.
E sec.
F sec.
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