In an operating, water-cooled, multi-box refrigeration system, both low discharge and high suction pressures are being simultaneously experienced. The probable cause for this condition is which of the following?

Correct Answer: Option C — discharge relief valve leaking back to the suction side

A leaking internal discharge relief valve bypasses high-pressure gas directly back to the suction side. This equalizes pressures, dropping discharge pressure while simultaneously elevating suction pressure due to the internal high-side leakage.