Neighbor's AirCon unit is loud
I live in a newly built estate with blocks around 300m2, meaning that houses are pretty close to each other. My master bedroom is on the side where my neighbor has his AirCon unit. I don't hear it during the day, but at night It's quite audible. And it changes tones as it turns on, and speeds up and then slows down. It is not too loud, but I'm irritated and can't get to sleep well.
I don't think that something is wrong with the unit, and i think my neighbor may not get me right with my questions. And I'm not sure what i can actually ask him. To move the unit somewhere? (We don't have backyards basically, so not very plausible). To buy a new one which is quieter (he may not be bothered with it at all). And who is gonna pay for it?
What do you think, what are my options?