u/AcceptablePaint191

I was adding more refrigerant to the ac system and noticed a cap was off on the circled part. What is that part called? I pressed down on it and liquid came out. Is a cap needed on there to prevent dirt and debris from getting in there?

Located in south central ID, USA.

Recently bought a hanging basket with flowers and noticed this flying bug hover around the flowers and looks to be sucking up pollen. Video shows it flying around, couldn’t get a still image. Is it harmful (i.e., will it try to attack if we get close to it or try to move the basket elsewhere)?