My central air unit was making a loud noise. The fan at the top was running and then it stopped and the noise got louder. If I let it sit for a while I can turn it back on, but it will only run for a few minutes. I turned the main power of to it, swept out from under it and in it, and even rinsed the vents out from the inside out. When it does run it still cools. Please help it is to be around 90 today.

If the fan stops running and won't come back on don't keep trying to get the unit to work. Call a repairman as the fan motor gave out. If after cleaning it like you said and it works, then the unit just needed a good clean out.