Installation, Maintenance & Repair Procedures Flashcards

When installing a condensing unit outdoors, what minimum clearance is typically required from walls and obstructions for proper airflow?

Answer: 24 inches on the discharge side, 12 inches on others

Condensing units require greater clearance on the discharge side (typically 24 inches) and at least 12 inches on intake sides to prevent recirculation of hot discharge air.

During a compressor replacement, you discover the old compressor failed due to a flooded start. What maintenance step should be added going forward?

Answer: Install a suction line accumulator

A suction line accumulator prevents liquid refrigerant from entering the compressor during startup, protecting against flooded starts.

What is the correct procedure when brazing a copper-to-brass fitting joint in a refrigeration system?

Answer: Use silver alloy filler with appropriate flux on the brass side

When brazing copper-to-brass, silver alloy filler (phos-copper works on copper but requires flux on brass) with appropriate flux on the brass side is required to prevent oxidation and ensure proper bonding.

A technician is retrofitting an R-22 system to R-407C. Which oil change is required?

Answer: Polyol ester (POE) oil must replace mineral oil

R-407C is an HFC refrigerant that requires POE oil because it is miscible with HFCs, whereas mineral oil is not compatible and must be removed.

When performing an oil change on a hermetic compressor, how is oil typically added to the system?

Answer: Through the suction service valve using an oil injector or pre-charged compressor

Hermetic compressors lack an external oil fill port, so oil is introduced through the suction service valve using an oil injector while the system is under vacuum.

What is the purpose of performing a triple evacuation during system commissioning?

Answer: To progressively remove moisture and non-condensables by alternating vacuum and dry nitrogen breaks

Triple evacuation uses alternating deep vacuum pulls and dry nitrogen breaks to progressively dilute and remove moisture and non-condensables more effectively than a single evacuation.

A scroll compressor is running but producing no cooling. Suction and discharge pressures are nearly equal. What is the most likely cause?

Answer: Scroll compressor running in reverse rotation

Scroll compressors rotating in the wrong direction (reverse rotation) will run but fail to build pressure differential, resulting in near-equal suction and discharge pressures.