I just moved into a new (old) house and my neighbor's HVAC unit is HUGE and LOUD - it looks like it must be industrial (a big yellow or orange drum about 6' high and 4' wide). I want to be a good neighbor, but something needs to be done and I'm not sure how to handle the situation. It seems to me having a unit this big (ie loud) is a code violation to start with and I'm wondering who would have installed it for them in the first place. Any advice about how to handle this? Any way to muffle the noise without causing them too much trouble.