well, i remember when the 2 girls were playing the game with him, and they kept imitating the hissing sound, by shushing. sorry, if i had been there, i would've heard it, and checked it out, but i am more aware of things around me, unlike him. and it is a story about an incredibly oblivious kid, so....
Sorry, but i love how you absolutely despise Hunter and Drew.
You just want them out of the picture by any means. And i get it, especially in Hunter's case. But, i just find it funny.
As for the air conditioner. I think you don't have to take it so seriously. Of course there are some inconsequential things, but it's a game. (And one of the main focus in the game is the humour.) If it would be realistic, there would be no story. The characters have to act a little dumb. Almost every fictional story has things like this to move the plot forward.
In addition, they show us when the air conditioner is hissing, because the dev wants us to know something is up. I don't think the hissing is that noticeable for the characters.
But, this is why i am really curious what will happen in the next chapters. The MC wants to start building his case against Hunter. And it will not be easy with now Drew in the house. So, he has to be resouceful because Hunter is willing to do anything to get the girls and Drew seems to be pretty smart. The other option is he gets some help. I mean other than Lucia. I think she is in game, if it's about to take down Hunter. But, I am not sure about Drew considering Lucia has a big trans/futa fetish.