To isolate a semihermetic compressor from system pressure:

To isolate a semihermetic compressor from system pressure:

• A. Front-seat the suction and discharge service valves.
• B. Close the stopping valve only.
• C. Open the relief valve and service port.
• D. Disconnect electrical power.

Answer: (A)

Isolating a semihermetic compressor from system pressure requires closing and properly seating both service valves on the suction and discharge sides. By front-seating these valves, you ensure the inner seats seal against the flow path, preventing any refrigerant pressure from the system from reaching or escaping from the compressor. This creates a true barrier on both sides, which is essential for safe maintenance and service. Closing only a stopping valve would leave one path open, so pressure could still be transmitted to or from the compressor. Opening the relief valve and service port would vent refrigerant rather than isolate it, which is unsafe and unnecessary for isolation. Disconnecting electrical power stops the motor, but it does not stop the refrigerant pressure in the lines connected to the compressor, so it doesn’t provide isolation from system pressure.

Isolating a semihermetic compressor from system pressure requires closing and properly seating both service valves on the suction and discharge sides. By front-seating these valves, you ensure the inner seats seal against the flow path, preventing any refrigerant pressure from the system from reaching or escaping from the compressor. This creates a true barrier on both sides, which is essential for safe maintenance and service.

Closing only a stopping valve would leave one path open, so pressure could still be transmitted to or from the compressor. Opening the relief valve and service port would vent refrigerant rather than isolate it, which is unsafe and unnecessary for isolation. Disconnecting electrical power stops the motor, but it does not stop the refrigerant pressure in the lines connected to the compressor, so it doesn’t provide isolation from system pressure.