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Refrigeration & Air Conditioning Mechanic Red Seal · Question

Upon completing a compressor replacement on a supermarket refrigeration rack, a technician evacuates the system to 750 microns. What is the primary reason for achieving such a deep vacuum before recharging?

Achieving a deep vacuum below 1000 microns is critical to remove non-condensable gases (like air and nitrogen) and moisture from the system. Moisture, if left i

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Question: Upon completing a compressor replacement on a supermarket refrigeration rack, a technician evacuates the system to 750 microns. What is the primary reason for achieving such a deep vacuum before recharging?

Answer options: ✅ To ensure all non-condensable gases, primarily air and moisture, are removed from the system.

  • To verify that the system is completely leak-free under negative pressure.
  • To prevent any residual oil from contaminating the new compressor.
  • To facilitate faster refrigerant charging by creating a pressure differential.

Correct answer: To ensure all non-condensable gases, primarily air and moisture, are removed from the system.

Explanation: Achieving a deep vacuum below 1000 microns is critical to remove non-condensable gases (like air and nitrogen) and moisture from the system. Moisture, if left in the system, can lead to acid formation, restricted expansion devices, and compressor burnout.

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