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1
During cooling operations, the demand for refrigerant tends to increase in proportion to an increase in the number of
operating indoor units (refrigerant in the accumulator decreases), though the change is small.
2
4
Having refrigerant in the accumulator, there is little change in discharge temperature when increasing or
decreasing refrigerant amount.
Compressor shell temperature is 20 to 70 k higher than low pressure saturation temperature when refrigerant
amount is adequate. When the difference between pressure shell temperature and low pressure saturation
temperature is smaller than 10k, overfilling of refrigerant is suspected.
3
Tendency of
discharge
temperature
change
In cooling operation, discharge temperature is more likely to
rise when operation load is high (outdoor temperature is high
etc.) than when indoor target temperature is set low.
The lower the operation frequency, the more likely discharge temperature will rise because of a
drop in compressor efficiency
Comparison including control
system.
1
The unit stops, displaying 1500 (refrigerant overfill) on remote controller.
Refrigerant Overfill
Insufficient
Refrigerant
2
Operating frequency does not reach its optimal level, resulting in insufficient power.
3
The unit stops, displaying 1102 (discharge temp. abnormality) on the controller.
4
Intermittent Fault Check Code 1243 is recorded in the error history.
1
Discharge temperature is high (over 125˚C)
Condition
Evaluation
Tend towards under fill
Tend towards overfill
2
Low pressure is extremely low
3
Inlet super heat is high (normal range = under 20K)
6
Discharge superheat is low (normal range = 20K and above)
4
5
Shell bottom temperature is high (The difference between low pressure
saturation temperature and shell bottom temperature is 70K or greater)
Shell temperature is low (The difference between shell temperature and
low-pressure saturation temperature is 10K or less).
6
6
. Refrigerant Amount Adjustment
1
1
Operating Characteristics and Refrigerant Amount
It is important to understand the relationship between refrigerant amount and operation characteristics. Use the fol-
lowing information when adjusting refrigerant amount.
[1] Operating Characteristics/Refrigerant Amount
2
2
Checking and Adjusting Refrigerant Amount
[1] Symptoms
The symptoms shown in the table below are possible signs of excess or lack of refrigerant. Be sure to adjust
refrigerant amount in the Refrigerant-Amount Adjustment Mode after determining the appropriate amount of
refrigerant to be added or drained by checking the operation status and performing self-diagnosis using LED.
[2] Refrigerant Volume
(1) Items to check during operation
Operate all the indoor units in cooling mode, and check discharge temperature, sub-cooling, low pressure,
inlet temperature, and shell-bottom temperature.
