What is superheat hunting?

Superheat hunting is a cyclical fluctuation in suction superheat due to varying refrigerant flow rate in the system. Superheat hunting is the result of the expansion valve (see Figure 1) excessively opening and closing in an attempt to maintain a constant operating condition.
Hunting can be seen indirectly by regular fluctuations in suction temperature, and in extremes, suction pressure.
Excessive hunting can reduce the capacity and efficiency of the system, resulting in uncomfortable conditions, loss of product, wasted energy, and ultimately, customer dissatisfaction.