Question 154Refrigeration & AC - 1st Asst/Chief

The correct answer is D) TXV hunting. Vapor bubbles in the liquid arriving at the thermal expansion valve (TXV) can cause the valve to "hunt" or cycle rapidly between open and closed positions. This is because the vapor bubbles reduce the density of the liquid, causing the TXV to open wider than necessary. This in turn results in the valve overcompensating and closing too much, creating an unstable, hunting cycle that can damage the needle and seat over time. The other options are incorrect because: A) freezing open would not occur due to the vapor bubbles, B) overheating is not a direct result of the vapor bubbles, and C) freezing shut is the opposite of the hunting behavior caused by the vapor bubbles.