Lately, I made some renovation on my house and concealed aircond pipe into the wall.

Suddenly aircond become not cold and I ask the guy who conceal the aircond to check but he was very busy then I call other person.

The new guy check and repair the aircond, but said that the aircond concealed with the nut. Later if want to service aircond, or change new aircond, I need to re hack wall again.

How can I know that which guy is true? Concealed with nut? Anybody can explain more?