I live in a rented 3rd floor apartment with central air/heat. Our 3 year old AC is terrible each summer. We set it at 70 - 72 and it cant keep up once it gets to the mid 80's. Trying to make it better for my 7 month old son, looking for suggestions. We keep electronics and lights off as much as possible, have covered, energy efficient windows, nothing helps. Would getting a blanket for our hot water heater help significantly? It's just in a closet off the living room. I think our biggest problem may be the cold air return. Our ac system is in a closet on our balcony. Air is pulled from our living room into a compartment that is the floor of the balcony closet, where air then goes into the ac unit. There is no ductwork, just mdf. It has no insulation, and the closet is not insulated. there is a big gap under the closet door and the mdf compartment isn't caulked well and has noticeable gaps in the seams. (it is also incredibly filthy in the compartment, which worries me with the new baby) How big of a role could this be playing and could someone tell me how to insulate it myself if I need to?