M thermal Split
26 202004
Midea M thermal Split
6 Special Control
6.1 Oil Return Operation
In order to prevent the compressor from running out of oil, the oil return operation is conducted to recover oil that has
flowed out of the compressor and into the refrigerant piping.
The oil return operation starts when the following condition occurs:
When the compressor cumulative operating time reaches 6 hours.
The oil return operation ceases when any one of the following three conditions occurs:
Oil return operation duration reaches 5 minutes.
Compressor stops.
Tables 3-6.1 show component control during oil return operation in cooling mode.
Component
Wiring diagram
label
4-16kW Control functions and states
Inverter compressor COMP
Runs at oil return operation rotation speed
DC fan motor FAN
Controlled according to cooling mode
Electronic expansion valve EXV
304 (steps)
Four-way valve 4-WAY
Off
Tables 3-6.2 show component control during oil return operation in heating and DHW modes.
Component
Wiring diagram
label
4-16kW Control functions and states
Inverter compressor COMP
Runs at oil return operation rotation speed
DC fan motor FAN
Controlled according to heating mode
Electronic expansion valve EXV
304 (steps)
Four-way valve 4-WAY
On
6.2 Defrosting Operation
In order to recover heating capacity, the defrosting operation is conducted when the outdoor unit air side heat exchanger
is performing as a condenser. The defrosting operation is controlled according to outdoor ambient temperature, air side
heat exchanger refrigerant outlet temperature and the compressor running time.
Table 3-6.3: Component control during defrosting operation
Component
Wiring diagram
label
4-16kW Control functions and states
Inverter compressor COMP
Runs at defrosting operation rotation speed
DC fan motor FAN
Off
Electronic expansion valve EXV
480 (steps)
Four-way valve 4-WAY
Off
6.3 Force Cooling Operation
The force cooling operation helps the refrigerant recovering before removal the water side heat exchanger.
The force cool mode can be ended by pushing the button on the outdoor refrigerant system main PCB FORCE
5s or this mode will be ended automatic if the system has operated force cool mode for more than 30 minutes.
Midea CAC
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