Condensation on the suction line occurs when its temperature is:

Condensation on the suction line occurs when its temperature is lower than the dew point. The dew point is the temperature at which air becomes saturated with moisture and can no longer hold all of its water vapor, leading to condensation. When the temperature of the suction line falls below this dew point, the moisture in the air surrounding the line condenses, forming water droplets on its surface.

In a residential air conditioning system, if the suction line is properly insulated, it should maintain a temperature that is lower than the dew point of the surrounding air in order to avoid condensation and potential water damage. If the suction line temperature is at or above the dew point, moisture will not condense on it, which is not the case here.

Therefore, recognizing the relationship between temperature and dew point is crucial for understanding why condensation occurs, and it emphasizes the importance of maintaining appropriate temperatures within air conditioning systems.