Refrigerant Amount Adjustment; Refrigerant Amount And Operating Characteristics; Adjustment And Judgement Of Refrigerant Amount - Mitsubishi Electric CITY MULTI PUHY-P200YEM-A Service Handbook

§

REFRIGERANT AMOUNT ADJUSTMENT

Clarify relationship between the refrigerant amount and operating characteristics of CITY MULTI, and perform service
activities such as decision and adjustment of refrigerant amount on the market.

[1] Refrigerant Amount and Operating Characteristics

The followings are refrigerant amount and operating characteristics which draw special attention.
During cooling operations, required refrigerant amount tends to increase (refrigerant in accumulator decreases)
1
in proportion to increase in the number of operating indoor units. However, the change of increase rate is small.
During heating operations, liquid level of accumulator is the highest when all the indoor units are operating.
2
Discharge temperature hardly changes when increasing or decreasing refrigerant amount with accumulator
3
filled with refrigerant.
During cooling operation at high ambient temperature the discharge
temperature may rise.
Tendency of
During heating operation at low ambient the discharge temperature
4
discharge
may rise.
temperature
The lower operating frequency is, the higher discharge temperature
tends to become of deteriorated compressor efficiency.
Compressor shell temperature is 10~60 K higher than low pressure saturation temperature (Te) when
refrigerant amount is appropriate.
5
Judged as over replenishment when temperature difference from low pressure saturation temperature (Te)
is 5 K or less.

[2] Adjustment and Judgement of Refrigerant Amount

(1) Symptom
The symptoms shown in the table below are the signs of excess or lack of refrigerant amount. Be sure to adjust
refrigerant amount in refrigerant amount adjustment mode, by checking operation status, judging refrigerant amount,
and performing selfdiagnosis with LED, for overall judgement of excess or lack of refrigerant amount.
Emergency stop at 1500 remote controller display (excessive
1
refrigerant replenishment)
Operating frequency does not fully increase, thus resulting in
2
insufficient capacity
Emergency stop at 1102 remote controller display (discharge
3
temperature trouble)
Excessive refrigerant replenishment
Insufficient refrigerant replenishment
- 72 -
Comparison including
control system