Hitachi RAM-71QH5, Service Manual

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FORCED COOLING
[Execution condition]
In order to accumulate refrigerant, units operate in cooling cycle.
Execution condition and operation status are shown below.
With neither indoor unit 1, 2, 3 and 4 not operated, when forced cooling switch is turned ON, forced cooling will be
performed.
[Operation status]
Outdoor unit fan: Fixed in LO.
[Note]
During forced cooling, if failure occurs in outdoor unit, thermostat is turned off. However, it is not counted.
The following shows the operation state of forced cooling.
Since rotation speed of compressor is fixed in 3000min -1 during forced cooling, steady speed period of compressor at start is
not performed.
Expansion valve/reversing valve : Set in normal conditions.
Compressor rotation speed: Fixed in 3000min -1 .
Always operation status of indoor units are monitored and forced cooling is inhibited when operation of any unit is detected.
MODEL RAM-71QH5
Power
Service switch
Request to Indoor
Power relay
Reversing
valve
Unit 1
Forced cooling request
Forced cooling request
Forced cooling request
Forced cooling request
Balancing request
Balancing request
Balancing request
Balancing request
Unit 2
Unit 3
Unit 4
Power
Outdoor fan
Compressor
rotation speed
520
Hold
Hold
Hold
Hold
[PSTARTC3
*
]
[PSTARTC3
*
]
480
Unit 1
Unit 2
Expansion valve
Unit 3
Unit 4
0
520
480
0
520
480
0
520
480
0
Turns on
for heating
Operation
Rust in prevention
[PSTARTC3
*
]
[PSTARTC3
*
]
<Td c N compen Diving control>
<Td c N compen Diving control>
<Td c N compen Diving control>
<Td c N compen Diving control>
80 sec
1S 1S 1S
100ms
15 sec
Balancing period 3 min
[TSKTM1_C
*
]
100ms
Initialization
TSKTM1_C and PSTARTC2$ are EEPROM data.