What does a crankcase pressure regulator do?

• A. It will not allow the compressor suction pressure to rise above the CPR setpoint.
• B. It increases compressor efficiency.
• C. It regulates liquid line temperature.
• D. It controls condenser fan speed.

Answer: (A)

The essential idea is to protect the compressor by keeping crankcase pressure from getting too high. A crankcase pressure regulator senses the pressure inside the crankcase and, if it rises above a preset value, opens a path to vent the excess vapor back into the compressor’s suction side. This keeps the crankcase pressure at a safe level and helps prevent issues like oil foaming, oil carryover into the suction, and potential bearing or seal damage. In normal operation, this means the suction pressure is kept within the regulator’s setpoint limits, avoiding excessive rise. It’s not about boosting efficiency, regulating liquid-line temperature, or controlling condenser fan speed, which are handled by other parts of the system.