Set and go: If it is hard to remember to tweak your thermostat before you leave for work, consider investing in a programmable thermostat or a timer for your window unit.
Time to replace? If your unit is more than 10 years old and you have substantial repair costs, it is probably time to consider a replacing your unit with a new, energy-efficient model. When replacing your A/C, look for a properly sized unit. If you install a unit that is too large, it will cycle on and off, reducing the efficiency of the system.