I keep my house at 65 deg all year long if you throw in some humidity then it can get to 68-69 deg I live in Oklahoma and it gets over 105 on a reg. if the house is insulated good and sealed up it helps a lot with energy consumption and if the ducting is done well good airflow, also if needed add a few fans to move the air more helps with cooling. 

I live in anaheim California, when it's hot out, my upstairs apartment seems to trap all the heat inside since the ceiling is wood beams, it gets so bad that even if I open up all the windows and doors, no air flows through here.

You'll have to ensure it has adequate air flow with the door closed from the ductwork above and possibly the sprinkler piping which is probably dictated by building coded in your area.

Thanks for advice, yeah it is definitely in the lease for them to change the air filters but believe it or not sometime they are incapable, can't even put it in the right away wrong air flow directions so I may hire someone to replace the air filters every 90 days esp when they have cats the air filters get clogged real fast, thanks!

Once we moved the furniture and boxes off the vents rooms got much cooler quickly.This isn't the first time this has happened with tenants complaining about poorly functioning air conditioning when the real problem was no air flow from items covering the vents.Gail

If not, then ask that the boxes go in the middle of the room, so that the inspector has access to the walls (also if there is an active leak, the last thing you want is a bunch of cardboard boxes against the wall impeding air flow).An inspector will not move anything for the inspection and they will miss things because nothing is 100% no matter who does it. 

For the smell, buy an ozone machine off amazon (have the unit empty while it is running-same with upstairs if the airflow is connected).

Chances are the tenant just wants more air flow through the place.

The new window can be opened for ventilation/air-flow, but there is a fan in this bathroom as well. 

To have air flow with no dead air.