Mitsubishi Electric CITY MULTI PUHY-400YMF-C Service Handbook page 127

Note: 1 If there are any units which are not operating, it will cause refrigerant to accumulate, so operate all the indoor
units. Also, in order to prevent stable operation from being disrupted by the thermostat going OFF, set the trial
operation mode.
Note: 2 If the high pressure is stabilized, it is safe to judge that the operation condition is stable.
Judge that operation is stabilized or not stabilized by whether the compressor starts after 3 or more minutes have
passed.
Note: 3 When turning on SW1 to
SW4-2 OFF : Variable Capacity Unit AL Display
SW4-2 ON : Constant Capacity Unit AL Display
Note: 4 If AL = 1 is indicates basically adjustment is not necessary, but when the liquid level is on the low side, in
AL = 1 region if one unit is stopped and refrigerant is accumulated in the unit it may result in there being
insufficient refrigerant, at such a time, adjustment is necessary.
Note: 5 Determine the difference in the volume of refrigerant necessary for cooling and for heating as follows.
supplementary charging in accordance with the table below.
* The piping length is the total pipe length calculated for a liquid pipe with a ø19.05 size.
Pipe Length 60 m or less 60 ~ 90 m 90 m or longer
Additional Refrigerant
19 kg
Volume
Note: 6 When turning on SW 1 to
SW4-2 OFF : Variable Capacity Unit AL Display
SW4-2 ON : Constant Capacity Unit AL Display
Note: 7 Middle capacity operation refers to the smallest indoor unit operation capacity attainable with the constant
capacity Unit. Unlike the outdoor unit models, operate about 70 % of the indoor units when operating the
constant capacity unit.
1 2 3 4 5 6 7 8 9 10
ON
, the LED will display the liquid level.
24 kg 29 kg
1 2 3 4 5 6 7 8 9 10
ON
, the LED will display the liquid level (AL).
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If the liquid pipe size is ø 15.88, the actual length is 0.85
If the liquid pipe size is ø 12.7, the actual length is 0.4
If the liquid pipe size is ø 9.52, the actual length is 0.2
If the liquid pipe size is ø 6.35, the actual length is 0.1
it the
Carry out