Being that it is temporary, I would get a small, free-standing a/c, such as those available at home centers, BJ's, etc. I believe they are plug-in (house current), and the installation consists of placing an (adjustable) frame with flexible exhaust duct, into the window opening. They are likely available in several sizes and should have general sizing information on the box. Being portable, when your watch is over, you can take it with you. Good luck. V

We are having the same problem with our older "WallMaster" unit by Friedrich. After cleaning both coils, filters, checking thermostat, etc finally broke down and called in a repair person. Sad news was that the compressor is going causing the unit to shut down before reaching the proper temperature. Try all the above suggestions, especially cleaning the filter, and a through cleaning of the units coils (both). Get a good thermometer (an instant read kitchen one will do), and check the difference between the incoming air (front of the unit), and what is being blown out. There should be at least a 12-20 degree difference. If the condenser comes on, but shuts down after about 10 minutes, you may have a problem with motor (condenser), in which case it would be cheaper to chuck the unit and buy new. In fact considering how inexpensive units can be,you may wish to look into getting a new one sooner rather than later. The last thing you want to do is purchase a new unit during a heat wave because your current AC died a slow painful death. If funds are tight check Craigslist for local people selling units. They may not be what you want, but it will get you through the summer, that way you can wait and get a good deal when stores are clearing stock in the late Fall.

Go to the condenser out side next to the house. There are two copper lines exiting the back of the condenser. One line will be larger than the other and be covered with a foam insulation. The insulated line is the suction line, returning refrigerant from the cooling coil. This line should be cool to the touch and sweating if there is a lot of humidity in the air. The smaller, non insulated line is the liquid line, refrigerant from the condenser to the cooling coil, and should be slightly warm to the touch. If it's hot, your condenser needs cleaning. Previous recommendations also apply about insulation, closed blinds, filters etc. this system is approaching the end of it's useful life, 15 to 20 years. It may just be shot!! Air flow does not change with age unless some one has added on to the house or made duct modifications without good advise. Another place to check is your blower. make sure the vanes are not clogged with dust & crud. This system worked at one time otherwise someone would have done something long before you moved in. Good luck

The contractor probably does not want to recalculate the load calculation because he may find a mistake and then you will use it against him. The calculation is probably correct. I am a little skeptical about the duct loss. What he has seems low. I would want an explanation on how that number was generated. There could be an additional 0.5 ton of loss that is missing just in duct losses. I am also concerned that this is the first time he has installed this equipment and in 5 trips he has not been able to solve the problem. When you talk to American Standard, tell them the contractor is having problems getting the equipment to work correctly. Installation issues are not their problem. Let them know you have a load calculation and the unit size is matched to the calculation, but the equipment does not seem to working as per the spec sheet. Tell them it is a new installation and with new duct work. Hopefully they will work with you and send someone to inspect the system.