I found water in my central cooling and heating vents does anyone know where this could be coming from?

Sounds like you have a AC condensate line that's clogged and the pan's overflowing into your ducts. But hey! Whadda I know? I'n just a plumber not a AC guy so I'm moving this so the AC experts can check it out. Good luck, Tom

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I found water in my central cooling and heating vents does anyone know where this could be coming from?

Up flow or downflow furnnace?
As speedball said have you checked your condensate line for restrictions?
When was the last time your unit was professionally serviced?

This one is way out in left field and may be irrelevant, but... last month I arrived at a home for routine a/c service and was greeted by a sewage-like odor. The homeowner explained that water had been leaking into the sub-slab duct system and the source was presumed to be the high water table in the area. They planned on having a French drain installed for a cool $2700 and hoped this would solve the problem. Moving along... the system was a counterflow arrangement, and I slid the evaporator out to clean it. The homeowner was washing some dishes in the kitchen sink, and I observed soap suds floating by in the ductwork. Turns out the sanitary pipe serving the kitchen sink was broken and dumping into the nearby duct. A plumber was contracted, the problem was repaired and bye-bye went the odor and humidity problems they had been living with for months. The guy who was going to do the French drain... well, he was a li'l bummed... but he'll live...

Been there before on that one. In slab duct is a good system but it does have its draw backs like improper install. If the duct was installed properly drain water could not get in unless it ran across the floor and into a register.

I wish I knew how to rate your answers that button is not showing at the bottom of each post just wanted to let you know called the plumber today and your replies will be very helpful thank you. I have not been running the air conditioning so (KC13) your idea sounds like it might actually be it. Thanks again everyone!