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7 Special Control
7.1 Oil Return Opera on
In order to prevent compressors from running out of oil, the oil return opera on is conducted to recover oil that has flowed
out of the compressor(s) and into the piping system. This opera on is performed for all units including units that are in
standby.
Timing of oil return opera on:
•
When the ini al cumula ve opera ng me reaches every 8 hours.
Tables 3-7.1 and 3-7.2 show component control during oil return opera on in cooling mode.
Table 3-7.1: Outdoor unit component control during oil return opera on in cooling mode
Component
Inverter compressor
DC fan motor
Electronic expansion valve
Four-way valve
Tables 3-7.3 and 3-7.4 show component control during oil return opera on in hea ng mode.
Table 3-7.3: Outdoor unit component control during oil return opera on in heating mode
Component
Inverter compressor
DC fan motor
Electronic expansion valve
Four-way valve
Table 3-7.4: Indoor unit component control during oil return opera on in hea ng mode
Electronic expansion valve
Note： Prevent cold wind： It's only valid in hea ng opera on, and this control is priority to other controls (including hea ng oil return and defrost),
Which determine the conversion between se ng fan speed with low fan speed and turn off the fan according to the evaporator coil temperature
T2.
Wiring diagram
label
COMP
FAN
EEV1
ST1
Table 3-7.2: Indoor unit component control during oil return opera on in cooling mode
Component
Fan
Electronic expansion valve
Wiring diagram label
Component
Unit state
Thermo on
Fan
Standby
Thermo off
Thermo on
Standby
Thermo off
28-56 model
•
Fixed frequency
•
Normal control as cooling opera on
•
Posi on 300 (steps)
•
Off
Unit state
Control func ons and states
Thermo on
Remote controller se ng
Standby
Remote controller se ng
Thermo off
Off
Thermo on
Normal control
Standby
300 (steps)
Thermo off
300 (steps)
28-56 model
•
COMP
•
FAN
•
EEV1
•
ST1
Control func ons and states
Operate on se ng fan speed (Prevent cold wind priority)
Operate on se ng fan speed (Prevent cold wind priority)
Off
Normal control
480 (steps)
480 (steps)
Control func ons and states
Control func ons and states
Fixed frequency
Fan speed controlled according to
heat exchanger temperature (T3) and
outdoor ambient temperature (T4)
Posi on 300 (steps)
Off
25
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