How do you keep cold air inside during the summer?

Question

I am renting an apartment and the apartment is over a four car garage. All windows are east and west. Last summer, it was 90 degrees in here with the central air set to 70. Yesterday, the temperature was 74 degrees outside and 79 degrees inside. I can't repeat last summer... Any tips for keeping the air in? I hung a thick cloth curtain with fleece backing over the stairwell on a tension rod, I put in a clean air filter, and I used air deflectors to shoot the air out instead of up on the floor vents. Any tips? We have 4 sets of windows with blinds closed all the time during the summer. If you recommend additional insulation, where's the best place to put it? Above? Below? Around? Is it expensive? I absolutely love my landlords and don't want anything too costly for their sake. Thanks!

There is a door at the bottom of the staircase which opens into a hallway which opens to the garage.

Answer 1

Assuming the AC unit has been serviced and operating correct. You may need a way to get rid of the hot air in the garage. The cars will put out a lot of heat as they sit there and cool. An exhaust fan would help remove some of the heat.
Windows that have the e-glass will cut down on the heat gain. If the owners won't replace the windows, maybe you could work out a trade and put the windows in yourself and deduct it from your rent? If they won't go for that, what about a heat reflecting film you can install on the inner panes?
Would they go for a window AC unit?
I know they want you guys comfortable, because you sound like good tenants. Hope you can work it out.

Answer 2

The problem is not keeping the cold air in but the hot air out. You have an open stair to the garage? See if you can ventilate the lower space better with a large exhaust fan and a way for air to enter the un-air conditioned space below. If there is no way to enclose the stair put an exhaust fan directly above the stair so hopefully the warm air will rise and go straight out the exhaust without mixing with your cool air. Is the air conditioner working at good efficiency, It may need freon, or servicing.
Insulation will certainly help, I would insulate as much as you can afford. The attic space, if there is one, would be first. Spray polystyrene insulation if there is no attic. Insulated glass next, then walls.

Answer 3

Unfortunately for your landlord the problem may not be your insulation. It's likely several things related to your heating and cooling system. 1. dirty evaporator coil. 2. dirty condenser coil (outdoor unit). 3. NO REFRIGERANT!!! The worst. 4. Bad metering device. I would call your local HVAC co. Preferably one that employs N.A.T.E technicians. North American Technician of Excellence. Good luck to you.