A hermetic recovery machine drawing a deep vacuum will

• A. Freeze the refrigerant
• B. Overheat due to reduced flow of refrigerant through the compressor
• C. Decrease power consumption
• D. Increase moisture in the oil

Answer: (B)

When a hermetic recovery machine pulls a deep vacuum, the suction pressure in the unit becomes very low. The refrigerant flow through the compressor depends on that suction pressure and on the return of oil with the refrigerant to lubricate and cool the moving parts. With a deep vacuum, the refrigerant is present mainly as vapor, oil return is hindered, and the overall flow through the compressor decreases. That reduced flow means the compressor has to work harder but isn’t being cooled or lubricated as effectively, so it can overheat.

The other scenarios don’t fit what happens under a deep vacuum in a recovery unit: vacuum won’t freeze the refrigerant, it wouldn’t typically cause a drop in power consumption, and it doesn’t inherently increase moisture in the oil.