During recovery, where should the low-side gauge be connected?

• A. The suction line
• B. The liquid line
• C. The discharge line
• D. The service port

Answer: (A)

The low-side gauge is used to monitor the pressure on the evaporator side of the system—the low-pressure side. When recovering refrigerant, you want to read the pressure on the side where vapor is returning from the evaporator, so you connect the gauge to the suction line. This lets you track how the system is depressurizing and ensures the recovery process remains within the low-pressure range.

Connecting to the liquid line would give you high-pressure liquid readings that don’t represent the low-side conditions, and connecting to the discharge line would measure the high-pressure side after the compressor, which isn’t useful for monitoring the low side during recovery. The service port exists on the low-pressure side, but the practical connection point for the low-side gauge during recovery is the suction line itself.