Defrost Control - Daikin SUPER MULTI NX G Series Service Manual

SiUS12-928_A

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
 The system is in heating operation.
 The compressor operates for 6 minutes.
 More than
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
Frequency
Compressor
Four-way valve
Fan
Electronic expansion
valve opening
(operating room)
Electronic expansion
valve opening
(stop room)
Function and Control
exchanger temperature.
minutes of accumulated time pass since the start of the operation, or ending the
previous defrosting.
reach the target heat exchanger temperature. (C)
0 Hz
60 sec.
ON
OFF
ON
OFF
ON
OFF
450 pulse
18 class
(minutes) 43
(Hz) 54
(Hz) 82
(seconds) 120
(pulse) 450
(pulse) 450
(pulse) 140
A B
Hz
Hz
120 sec.
650 sec.
5 sec.
pulse
pulse
24/32 class
38
39
62
60
350
400
160
Control Specification
C
PI control
sec.
5 sec.
pulse
Initial opening
Initial opening
0 pulse
(R12296)
52