The AC fan is probably still under a manufacturer's warranty. Check the packet of warranties for the AC unit and the dishwasher. You may be covered for some of the equipment costs.
If the builder is still on site you might be able to get him to fix the other little problems.
However, the septic tank--if it's still bubbling up--should be inspected by a septic tank inspection company. 3 years is kind of quick to have to drain it. If the leach field is bad or the tank isn't functioning properly it can be expensive to fix.
Similarly with the windows. If they are leaking water, the flashing around them could be installed wrong. That's a big problem that could require removing all the windows and redoing the flashing around each one. If the "leaking" is air, it means either very cheap windows or installed improperly.
I would get on this quickly in case the builder decides to go into bankruptcy. Either way, you need to know what's happening with the septic tank and windows ASAP. It might not be a bad idea to have a home inspector check the entire house out for things like: improperly sloped drainage from the house, plumbing, electrical, proper roof installation and flashings around roof penetrations, exterior door seals, etc. The home inspector may be certified to do window leak tests. Ask them.
Even if you don't get any help from the builder, at least you know what to expect and can set a schedule for repairs over the next few years instead of getting calls from tenants and having to come up with big unexpected repair money.