Water in Flex Ducts

[Coma]

My buddy bought a house about 8 months ago. A couple weeks ago we wre doing some clean up and found a down spout was not draining properly, leading to some potential water getting into a foundatian vent. We crawled under the house to check things out and found one of his HVAC flex ducts had fallen down and really wet. We initially had no idea why it had fallen, but suspected it had gotten wet laying on the ground. The crawl space was damp, but not what I would consider significantly.

While pondering our action plan, I noticed another duct sagging. Upon inspection I found it very heavy. I poked the outer plastic and water just drained out. Almost all had varying degree of water in them. Now we feel that the 1st duct pulled away from the register due to the weight within the flex-Duct.

I have not yet concluded if the water is only in the vapor barrier/insulation or the internal duct as well.

Here's some key -

House has a crawl space on a small slope from 2-4 ft headroom.
Other than the downspout issue, I would consider it to have good drainage away from the house.
HVAC unit is a about a 91 model, under the house, and otherwise functioning well.
Condensate does drain to the outside and while not sure if it is restricted, I did see it dripping this summer..
House location is not subject to any possibility of flooding.
The old lady owning the house previously swears there was never any internal flooding, like a broken pipe, tub, or sink.
Main trunkline is tin, though not sure if it is insulated.

The home inspector did not pick up on this before the purchase of the house, though that doesn't suprise me.
The Home Warranty won't cover it because the service guy says it had to happen from an internal flood or malicious activity.

We have talked to numerous collegues in the business, and no one seems to have a conclusive answer.

Replacing the ducts is no big deal, but we just want to know what to do to ensure this does not re-occur.

Any conclusive experience??

[heatseeker]

Remember that dude from the insurance company does not have your best interest as the num. 1 priority. The water is probably from a clogged drain from the evap coil, or a dirty evap coil or a broken drain pan or an undercharged system. The insurance will leave you out to dry. Get a second opinion and pay for the service call.

[Coma]

So your saying that it is humidity build-up in the flex duct over time?
Because the unit is way lower than all the duct work.

[heatseeker]

No I'm not saying it's from humidity over time. It's from one of the problems that I listed in my last post. Air cond. always removes moisture from the air but if there is secondary problems it will end up in your ductwork. Usually not a tough repair if you know what you are doing.

[Freon]

Check all ducting and make sure it's well insulated. Check the supply plenum and the pan under the evaporator coil. Is there standing water in the pan? Is any supply duct exiting the supply plenum lower than 6" from the bottom of the plenum. Has there been any widespread flooding in the last few years?