Suction pressure too high in relation to the expected evaporation pressure.
Check the calibration of the suction pressure regulating valve. If the unit is equipped with a conventionally charged expansion valve and a suction pressure regulating valve is not present, check that the thermostatic bulb of the expansion valve is securely attached to the suction piping and is properly lined. Check that the valve is correctly calibrated (overheating between 4 and 8ºC) and is not overpowering. If the unit is equipped with an MOP-loaded expansion valve, excessive suction pressure may be caused by opening the valve itself too much, may not be properly calibrated (insufficient overheating) or may be overpowered. Take appropriate action. If the unit is a capillary type, excessive suction pressure is caused by overload.
