Mold and mildew make easy breeding grounds of air conditioner filters, which can occur from improperly-cleaned AC units and window-mounted units that are exposed to humid outside conditions. The built-up mold and other particles are blown into your home and cause health problems for those allergic to the airborne particles. Breathing mold can also cause respiratory difficulty and infection in the young, the elderly and others with weakened immune systems.
A Blow to the Electrical Bill
A window air conditioning unit that is improperly sealed or placed incorrectly can significantly raise your monthly electric bill because the appliance must work harder to cool the room since all the cold air generated by the air conditioner is escaping through open seals or spaces in the window. The website for Green Energy Efficient Homes recommends purchasing government certified Energy Star air conditioners to ensure that your electric bill isn't mortally wounded during the summer months. Inexpensive window-mounted units may have a lower initial cost but will end up costing you more in the end because of inefficient operation.
Damages to Property
Window unit air conditioners that are improperly installed or placed in windows that are too small or too big for them can significantly damage your property. Air conditioner units that fall out of windows that are too big for them can take some of your window's wood with them, costing you not only a new air conditioner but a new window frame. Air conditioners that are too small can actually cause window panes to crack or shatter when drilled into place because of the added pressure. It's necessary to measure your window and find an air conditioner of appropriate size to avoid these potential damages.