Daikin E Series, Service Manual

Page: 99 / 453

Special Control SiAU18-715
86 Function
3.3 Defrosting Operation
The defrost operation is performed to solve frost on the outdoor unit heat exchanger when
heating, and the heating capacity is recovered.
[Conditions to start]
The defrost operation is started referring following conditions.
Š
Outdoor heat exchanger heat transfer co-efficiency
Š
Temperature of heat-exchange (Tb)
Š
Low pressure equivalent saturation temperature (Te)
Š
Timer (2 hours at the minimum)
In addition, outdoor heat-exchange co-efficiency is derived from Tc, Te, and the compressor
load.
* From the preparing operation to the defrost operation, and from the defrost operation to the
operation after defrost, the compressor stops for 2 min. to reduce noise on changing of the four
way valve.
Outdoor unit actuator
Defrost preparation
operation
Defrost operation Post Defrost operation
Compressor Upper limit control 124 Hz Full load
2-step increase from
36 Hz Unload to
(Pc - Pe>0.4 MPa)
every 20 sec.
Outdoor unit fan STEP8 OFF STEP8
Four way valve ON OFF ON
Main electronic expansion valve
(EV1)
SH control 480 pls 55 pls
Subcooling electronic expansion
valve (EV3)
0 pls 0 pls 0 pls
Hot gas bypass valve (SVP) OFF ON ON
Ending conditions 2 min.
•
15 min.
•
Tb>11°C
•
Ts1 - Te<5°C
•
160 sec.
•
Pc - Pe>0.4MPa
or
&
{
or
Indoor actuator During defrost
Indoor unit fan
Thermostat ON unit OFF
Stopping unit OFF
Thermostat OFF unit OFF
BP unit electronic expansion
valve
Thermostat ON unit SH control
Stopping unit 80 pls
Thermostat OFF unit SH control