Daikin FCQ18PVJU Service Manual page 30

Special Control
3.2.2 Oil Return Operation in Heating Operation
[Conditions to start]
The heating oil-returning operation is started under the following conditions:
 Integrated amount of displaced oil
 Timer
Outdoor Unit Actuator
Compressor
Outdoor unit fan
Four-way valve
Main electronic expansion valve
(EV1)
Subcooling electronic expansion
valve (EV2)
Hot gas bypass valve (SVP)
Receiver gas discharging valve
(SVG)
Ending conditions
* From the preparation of the oil-returning operation to the oil-returning operation, and from the
oil-returning operation to the operation after oil-returning, the compressor stops for 1 minute to
reduce noise when changing the position of the four-way valve.
Fan
Electronic expansion valve
23
(After the power is turned on, integrated operating-time is 2 hours and subsequently every 8
hours.)
In addition, the integrated amount of displaced oil is derived from Tc, Te, and the
compressor load.
Oil return preparation
operation
Upper limit control
STEP 8
ON
SH control
0 pls
OFF
ON
130 sec.
Indoor unit actuator
Thermostat ON unit
Stopping unit
Thermostat OFF unit
Thermostat ON unit
Stopping unit
Thermostat OFF unit
Oil return operation
124 Hz
OFF
OFF
1400 pls
0 pls
ON
ON
• 6 min.
or
• Ts - Te<5
Heating oil return operation
SiUS28-902_a
Post-oil-return operation
2-step increase from
52 Hz to
(Pc - Pe>58 psi) time
STEP 8
ON
200~400 pls
0 pls
ON
OFF
• 160 sec.
or
• Pc - Pe>58 psi
OFF
OFF
OFF
500 pls
500 pls
500 pls
Function