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Refrigeration & Air Conditioning Mechanic Red Seal · Question

A maintenance technician is checking an R-134a refrigeration system and notices the sight glass is continuously bubbling. After ruling out an expansion valve issue, what is the most likely cause and corresponding action?

Continuous bubbling in the sight glass typically indicates that there is insufficient liquid refrigerant in the liquid line, often due to a low refrigerant char

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Question: A maintenance technician is checking an R-134a refrigeration system and notices the sight glass is continuously bubbling. After ruling out an expansion valve issue, what is the most likely cause and corresponding action?

Answer options: ✅ A low refrigerant charge; add more refrigerant to the system.

  • An overcharged system; recover some refrigerant.
  • A clogged filter drier; replace the filter drier.
  • Non-condensable gases in the system; purqe the non-condensables.

Correct answer: A low refrigerant charge; add more refrigerant to the system.

Explanation: Continuous bubbling in the sight glass typically indicates that there is insufficient liquid refrigerant in the liquid line, often due to a low refrigerant charge. Adding refrigerant will fill the line and eliminate the bubbles, assuming other components are functioning correctly.

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