Which characteristic may result from a throttling valve set too low?

When a throttling valve is set too low, it can create a bottleneck in the refrigerant flow within the system. This restricted flow can lead to insufficient refrigerant reaching the evaporator coil, which reduces the amount of heat that can be absorbed and thus limits the overall heating and defrosting capacity of the unit. As the refrigerant cannot effectively absorb heat, the performance of the heating and defrosting functions suffers, leading to decreased operational efficiency. This characteristic is critical to understand, as optimal settings for the throttling valve are crucial for maintaining the required heating performance in refrigeration and climate control systems.