High superheat indicates what about the liquid level in the evaporator?

High superheat indicates that the vapor leaving the evaporator has gained additional heat beyond the saturation point, which typically suggests that not enough liquid refrigerant is present to absorb heat efficiently. When the liquid level is low, there is insufficient refrigerant to fully change to vapor form, leading to an increase in temperature of the vapor before it exits the evaporator. This condition can lead to inefficient system operation and potential compressor damage.

In contrast, a normal or high liquid level would ensure that the refrigerant can adequately absorb heat, maintaining lower superheat levels. Therefore, a high superheat reading is a clear signal of a low liquid level in the evaporator.