Points of Analysis Si30-408
184 Service Checker Type3 Application Edition
(Case Example) EXIII: Abnormal discharge pipe temperature
Unit supplied: RSXYJ140KC (Japanese domestic model) equivalent to RSXY5K.
Malfunction conditions:
The compressor stops due to the abnormal high temperature of discharge pipe (F3)
approximately once a week.
Discharge pipe temperature control
When the compressor reaches the discharge pipe temp. of Td − Tc > 35°C, the liquid
injection will turn ON. When the discharge pipe temp. becomes Td − Tc < 15°C, the liquid
injection will turn OFF. However,for a period of five minutes after the completion of
compressor startup, oil return operation, or defrost operation, liquid injection is conducted on
all compressors which have started.
(Td: Discharge pipe temp., Tc: High pressure equivalent saturation temperature)
Referring to the Checker data (graph shown below)
Even though the compressor reaches the discharge pipe temp. of Td − Tc > 35°C, liquid
injection is not activated. (This time, no data on compressor stop due to malfunction could be
collected.)
Cause of malfunction
Since the compressor was shipped with a ROM for test unit use installed at the factory, even
though the compressor reached the discharge pipe temp. of Td − Tc > 35°C, liquid injection
was not activated. It is supposed that the discharge pipe temperature rose due to the long-
term operation of the compressor, thus resulting in the compressor stop due to F3
Malfunction (Abnormally high temperature of discharge pipe).
Countermeasure
The compressor returned to the normal operation by rewriting the ROM data.
Liquid injection does not turn ON.
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