Coast Guard Exams
Question 23Refrigeration/AC - Assistant Engineer70% to pass

If the superheat setting of a thermostatic expansion valve is set too low, what would be the result, assuming that the system has a single evaporator?

AI Explanation
The correct answer is C) the suction line will be abnormally cold and liquid may flood back to the compressor. If the superheat setting of the thermostatic expansion valve is set too low, it will allow more liquid refrigerant to enter the evaporator than necessary. This excess liquid refrigerant will cause the suction line to become abnormally cold, as more liquid refrigerant is being vaporized in the evaporator than can be properly handled by the compressor. This liquid floodback to the compressor can potentially damage the compressor. The other answer choices are incorrect because: A) a low superheat setting would not result in an abnormally high receiver level, B) the box temperature would not be pulled way down, and D) the suction line would be abnormally cold, not warm.