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1.  Measuring temperature 
1)  Indoor unit suction temperature, release temperature, temperature difference, → Measure by thermometer 
2)  2-way valve pipe temperature in cooling mode is low temperature (benchmark:5 ~ 10°C), in heating mode 
is medium temperature (benchmark:25 ~ 35°C). 
3)  3-way valve pipe temperature in cooling mode is low temperature (benchmark:7 ~ 15°C) in heating mode is 
high temperature (benchmark:38 ~ 50°C). 
2.  Measuring electric current 
  Measuring electric current in operation → check by clump meter (refer to table of technical characteristic 
guideline) 
3.  Meauring pressure 
  Measuring gas pressure → check the pressure by manifold gauge (refer to table of technical characteristic 
guideline) 
4.  Any sound from the expansion valve? 
(when starting the operation and the outdoor unit is turned on, the expansion valve is re-set, check if there is any 
edged sound or clack sound) 
13.8.3  Guidance for diagnosis of refrigerant cycle 
Comparison with 
normal operation 
Cooling mode 
High  Low 
Refrigerant 
pressure 
Excess insertion of refrigerant  Clogged capillary, expansion valve malfunction 
Heat releasing obstruction  Clog by moisture 
Dirty condenser, attachment of impurity  Lack of refrigerant gas 
Compressor malfunction   
Operation electric 
current 
Excess insertion of refrigerant  Lack of refrigerant gas 
Heat releasing obstruction  Compressor malfunction 
Dirty condenser, impurity  Mixture of air 
  (Insufficient evacuation) 
2-way valve 
temperature 
Excess insertion of refrigerant  Clogged capillary, expansion valve malfunction 
Compressor malfunction  Lack of refrigerant gas 
3-way valve 
temperature 
Lack of refrigerant gas • Compressor malfunction  Excess insertion of refrigerant 
Clogged capillary, expansion valve malfunction   
 
Suction 
temperature 
& 
Release air 
temperature 
Temperature difference at or less than 8°C in cooling operation • • • Causes 
  • Heat releasing obstruction    • Dirty condenser    • Attachment of impurity 
  • Lack of refrigerant gas    • Excess insertion of refrigerant     
  • Mixture of air    • Mixture of moisture     
  • Clogged capillary    • Expansion valve malfunction    • Compressor malfunction 
 
◎  Above all are based on the condition that the installation work is properly performed (no issues in indoor / outdoor 
pipe connections, etc.)