ive had mine on for a week or so. it is recommended that you have your a/c checked each season to help prevent future problems, alltho not everything can be prevented. if your low on freon ect., you can catch it from the get go. also, when you turn your a/c on and off, it makes the equipment work twice as hard. not really good on the equipment, because it has to pull all the humidity back out of the house, and its alot cheeper on the wallet to just leave it on. usually when i turn mine on, its on for all summer. my bill is usually 50-60 dollars a month in the summer. also, covering the unit causes the unit to hold moisture and starts the rusting quick. anyways, i tell all my customers this. if any1 needs a check, just let me know................