Midea MV6-i400WV2GN1-E - Oil Return Operation; Special Control; Timing of Oil Return Operation

V6-i VRF 50/60Hz
45
Part 3
- Control
7 Special Control
7.1 Oil Return Operation
In order to prevent compressors from running out of oil, the oil return operation is conducted to recover oil that has
flowed out of the compressor(s) and into the piping system. This operation is performed for all units including units that
are in standby. When the outdoor unit is running in oil return, the digital display on outdoor main PCB will display “d0”.
Timing of oil return operation:
 When the initial cumulative operating time reaches 140 minutes and then every 8 hours.
Tables 3-7.1 and 3-7.2 show component control during oil return operation in cooling mode.
Table 3-7.1: Outdoor unit component control during oil return operation in cooling mode
Component
Wiring
diagram label
8-12HP
14-18HP
20-24HP
26-28HP
30-32HP
Control functions and states
Inverter compressor A
COMP(A)
●
●
●
●
●
Fixed frequency
Inverter compressor B
COMP(B)
●
●
●
DC fan motor A
FANA
●
●
●
●
●
Fan speed controlled according
to discharge pressure
DC fan motor B
FANB
●
●
●
Electronic expansion valve A
EXVA
●
●
●
●
●
Position 480 (steps) or 3000
(steps)
Electronic expansion valve C
EXVC
●
●
●
●
●
Position 96 (steps)
Four-way valve
ST1
●
●
●
●
●
Off
Solenoid valve (oil balance)
SV4
●
●
●
●
●
Normal control
Solenoid valve (fast defrosting)
SV5
●
●
●
●
●
On
Solenoid valve (EXV bypass)
SV6
●
●
●
●
●
On
Solenoid valve (indoor units
bypass)
SV7
●
●
Normal control
Solenoid valve (inverter
compressor A vapor injection)
SV8A
●
●
●
●
Controlled according to inverter
compressor A
Solenoid valve (inverter
compressor B vapor injection)
SV8B
●
●
Controlled according to inverter
compressor B
Solenoid valve (inverter
compressor B pressure balance)
SV9
●
●
●
Open before compressor B
startup
Table 3-7.2: Indoor unit component control during oil return operation in cooling mode
Component
Unit state
Control functions and states
Fan
Thermo on
Remote controller setting
Standby
Off
Thermo off
Off
Electronic expansion valve
Thermo on
Normal control
Standby
300 (steps)
Thermo off
300 (steps)