Hitachi RAM-52QH5, Service Manual

Page: 55 / 104

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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 and 3 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, compressor fixed speed control 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.
Power
Heating output
Service switch
Cooling output
Outdoor fan
Turns on
for Cooling
Operation
Power
Compressor
rotation speed
In-rush Prevention
Compressor
P
o
w
er rela
y
Electric e
xpansion valv
e
Main microcomputer
R
e
ve
rsing
valv
e
Unit 1
Unit 2
Unit 3
Unit 1
Unit 2
Unit 3
Hold
Hold
Hold
Approx.100ms
100ms
1sec.
1sec.
1sec.
520
480
0
520
480
0
520
480
0
TSKTM1_C and PSTARTC2$ are EEPROM da ta.
Hold 500ms
Hold 500ms
Hold 500ms
31.25PPS
PSTARTC2$
PSTARTC2$
PSTARTC2$
Initialization
finished
[Outdoor temperature < 40˚C]
[Outdoor temperature < 40˚C]
[Outdoor temperature < 40˚C]
Initialization
finished
< TD control + N compensation + Diving control >
< TD control + N compensation + Diving control >
< TD control + N compensation + Diving control >
TSKTMI_C1 Outdoor temperature
≥
STARCTP_C
TSKTMI_C2 Outdoor temperature
≤
STARCTP_C
Forced cooling request
Forced cooling request
Forced cooling request
Balancing request
Balancing request
Balancing request
Balancing period 3min.
Lo
3000min
-1
15sec. +sub
30sec.
80sec.
MODEL RAM-53QH5