Daikin RXYQ5-48MAY1, Service Manual

Page: 99 / 352

Special Control Si39-407
88 Function
3.3 Defrosting Operation
To defrost the outdoor unit heat exchanger while in heating operation, the defrost operation is conducted to recover the
heating capacity.
[Start conditions]
Referring to the set conditions for the following items, start the defrosting operation.
• Heat transfer coefficient of the outdoor unit heat exchanger
• Heat exchange temperature (Tb)
• Timer (Set to two hours at minimum.)
Furthermore, the heat transfer coefficient of the outdoor unit heat exchanger is computed from Tc, Te, and compressor
loads.
*
In the case of multi-outdoor-unit system,
Master unit: Performs the operations listed in the table above.
Slave units: Operating units perform the operations listed in the table above.
Non-operating units perform the operations listed in the table above from the Defrost operation.
(Non-operating unit stops during “Defrost preparation operation”.)
* Actuators are based on RXYQ16MA.
Outdoor unit actuator
Defrost preparation
operation
Defrost operation Post Defrost operation
Compressor Upper limit control 143 Hz + ON + ON
1-step increase from
(74 Hz + OFF + OFF) to
(Pc - Pe>0.4 MPa)
Outdoor unit fan
STEP7
or
STEP8
OFF STEP8
Four way valve ON OFF ON
Main motorized valve (EV1) SH control 2000 pls 200 pls
Subcooling motorized valve (EV2) 0 pls 0 pls 0 pls
Hot gas bypass valve (SVP) OFF ON ON
Oil equalization valve (SVO) ON ON ON
Receiver gas discharging valve
(SVG)
OFF OFF OFF
Non-operating unit liquid pipe stop
valve (SVSL)
ON ON ON
Ending conditions 130 sec.
•
12 min.
•
Ts >11
°
C
•
160 sec.
•
Pc - Pe>0.4MPa
or or
Indoor unit actuator During defrost
Fan
Thermostat ON unit OFF
Stopping unit OFF
Thermostat OFF unit OFF
Electronic expansion valve
Thermostat ON unit 512 pls
Stopping unit 512 pls
Thermostat OFF unit 512 pls