System control Si18-201
122 Main Functions
3.8 Defrost Operation
Outline During heating operation, the outdoor heat exchanger intermediate temperature of a frosted unit
is estimated based on the outdoor temperature and compressor output frequency. If the outdoor
heat exchanger intermediate temperature is lower than the estimated defrosting temperature,
the unit is considered to be frosted; therefore, the compressor is stopped and the cooling cycle
is activated for a defrosting operation (reverse cycle defrost). The defrosting operation stops
when a certain time elapse or when the outdoor heat exchanger liquid pipe temperature
reaches the preset temperature level.
Details
TD1(47min)
Defrost
preventing
timer
FDS
Defrost requesting
flag
FD
Defrosting flag
Compressor
MRC / W
4-way valve
Outdoor fan
EVP
EVG
EVL
QAD
BP motorized valve
target flow rate
QAHD
BP bypass motorized
valve target flow rate
Cumulative
time of continuous
normal operation
TD2(15min)
TD3(60sec)
TD3(60sec)
ON
OFF
ON
OFF
ON
OFF
Defrost
decision
continuing
timer
TD5(60sec)
TD10(60sec)
OHz OHz
TD7(2min)
TD6(3min)
TD9(4.5min)
48Hz
65Hz
1
0
1
0
Upper fan (0rpm) Lower fan (0rpm)
(2min)
70 pulses
150 pulses
450 pulses
450 pulses 450 pulses
190 pulses
100 pulses
TD5R(5sec)
(M1012)
Full close
0 pulse
To standby operation
When starting-up of heating
TD10R(5sec)
Leaving timer for
4-way valve switching
Compressor
operation
frequency
Delay timer for 4-way valve switching
Defrost
entering
stop timer
Defrost cancel
prohibit timer
Defrost continue
timer
Compressor stop
To Next Page
Loading...
Need help?
General