Toshiba MMU-AP0091H service manual Operation mode Outline

Functional part name			Functional outline
Pressure	High pressure sensor	(Connector CN501: Red)
sensor		1) Detects high pressure and uses it to control the capacity of the compressor.
		2)	Detects high pressure during all cooling operation and uses it to control the fan when cooling
			with low outside air.
		3)	Detects under-cool of the indoor unit of which heating thermo.-ON during all heating operation
			and simultaneous operation.
		4)	Controls outdoor fan rpm during mainly cooling, part heating operation.
	Low pressure sensor	(Connector CN500: White)
		1)	Detects low pressure and uses it to control capacity of the compressor during all cooling
			operation and simultaneous operation
		2)	Detects low pressure and uses it to controls super heat during all heating operation and
			simultaneous operation
Heater	Compressor case heater	(Compressor 1 Connector CN316: White, Compressor 2 Connector CN315: Blue)
		1)	Prevents liquid accumulation in the compressor
	Accumulator case heater	(Connector CN321: Red)
		1)	Prevents liquid accumulation to accumulator
Balance pipe		1) Oil balancing pipe between outdoor unit (This unit does not use this Balance pipe.)

Operation mode

	Operation mode	Outline
1.	All Indoor Unit(s)	Only cooling operation without heating operation
	Operating for Cooling	Outdoor heat exchanger (Main heat exchanger) is used as a condenser.
2.	All Indoor Unit(s)	Only heating operation without cooling operation
	Operating for Heating	Outdoor heat exchanger (Main heat exchanger) is used as an evaporator.
3.	Simultaneous operation	MIU for simultaneous operation
	3-1. Mainly cooling, partly	Cooling/heating simultaneous operation with subjective cooling operation
	heating operation	Outdoor heat exchanger (Sub heat exchanger) is used as a condenser.
	3-2. Mainly heating, partly	Cooling/heating simultaneous operation with subjective heating operation
	cooling operation	Outdoor heat exchanger (Main heat exchanger) is used as an evaporator.
4.	Defrost	Using the reversing operation of the 4-way valve, ice on the outdoor heat exchanger is
		dissolved within a single cooling cycle.

For details of operation mode, refer to page 53 to 59.

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