Charging liquid HCFC-123 into a system under a deep vacuum could cause what to happen unless necessary precautions are taken?

Correct Answer: Option C — system secondary refrigerant to freeze

Charging liquid HCFC-123 into a deep vacuum causes rapid flash evaporation and intense localized chilling. In chillers utilizing secondary coolants like water or glycol, this extreme temperature drop can freeze the secondary fluid, causing evaporator tube rupture.