Additional information regarding the COMPRESSOR CHECKLIST
Check item
Additional information (Mechanism of compressor failure)
1 and 2
The liquid refrigerant return volume to the compressor is controlled by the discharge gas temperature Td1 when only compressor
No. 1 is operating. If Td1 and Td2 are reversely connected, the liquid refrigerant return volume will be small by detecting the
temperatures even if the actual temperature of the discharge gas is high. Therefore, this abnormal overheating operation will cause
the insulation failure on the motor winding.
3, 4 and 5
The overcurrent control (operating frequency control) is carried out by current detected by the current sensor. In this case, a winding
insulation failure will occur, since control is not available in spite of the high current.
6 and 7
The current sensor checks the phase and adjusts the output of the electrical wave, as well as what has been described above. If a
fault occurs, the electrical wave output becomes unstable adding overload to the motor windings and causing winding insulation
failures.
8 and 9
During the cooling operation, Pd is controlled by the fan revolution of the indoor unit, and Td and SH are controlled by MV for each
of the indoor units.
During the heating operation, Td and SH are controlled by MV1.
If the expansion valves are improperly connected, proper control is not available, resulting in compressor seizure depending on the
liquid refrigerant return conditions or motor winding insulation failure depending on the overheating conditions.
10
If the refrigeration cycle and the electrical system are improperly connected, the suction pressure operation is maintained abnormally
low or the discharge pressure operation is maintained abnormally high, resulting in an increase in compressor overload, since its
proper control is not available.
11
The same
12
The compressor may be locked due to the liquid return operation during the cooling operation.
13
In the case that the contact resistance becomes big, the voltage imbalance between phases will cause an abnormal overcurrent.
14
In this case, an overcurrent will occur, the efficiency will be reduced or the motor winding will heat up excessively.
15
In this case, the motor will burn up or compressor seizure.
8 Troubleshooting
273
SMGB0065 rev. 1 - 12/2010
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