Evaporative Water Coolers - Dripping from duct

I have a roof mounted swamp cooler that has a leaking or dripping problem that I can't figure out. I purchased my home last year and when I turned on the swamp cooler I had a major leak. I used the recommended paint and sealed up the pan and replaced the float and drain in the pan. It works great but I have this leak/drip that keeps happening. It doesn't happen when the cooler is running, it happens 2, 3, or 4 days after the cooler was last run. I had a new roof put on last year and just had the roofer out yesterday because I had the same leak/drip problem happen.

When the leak happened last year I had to tear out part of the ceiling directly under where the unit is mounted on the roof. I never replaced the sheet rock because I kept having the dripping problem and I wanted to make sure I had it fixed before putting in new sheet rock. The roofer also agrees that the leak isn't coming from the pan. He thinks it is due to condensation building up and then it runs down and drips off the duct. He said something about cooler air and water in the pan and the heat in the attic causing condensation. I ran the cooler when he was here so he could check it out.

Could part of the problem be that there is a section of ceiling missing? I just have it covered with plastic so there is no insulation over the area which allows heat to rise. There was no leaking all winter from the area but I ran the swamp cooler one day last week and then 3 days later the dripping started.

If it only does it after the cooler sits for several days, then it is because your float is dripping and raising the water level to a point that is leaking into the house. Is this a downdraft cooler? Probably whoever installed it put screws through the duct below the blower housing.
If this cooler is old, I would think about replacing it. The problem is not condensation.

I don't think it is the float. We shut the water off to the cooler when we aren't running it so I don't think it would be over filling, and I put a new float on last year. The water isn't coming out of the bottom of the duct. You can see where it runs down the outside of the duct and drips off of it.

Condensation is warm humid air in contact with a cooler surface. If you have exposed (not insulated) cooling ducts in the attic, I would think energy loss and condensation would be problems. The three days is still a question, but I have seen water leaks that take time to migrate to a point where then appear as a leak. Do you have fiberglass insulation in the attic and is it wet?

Bud

Right now there is no insulation under the cooler duct. When we had the leak last year we tore out a section of the ceiling and the blown in insulation under the duct. I'm completely stumped by the leaking. When it leaks there is no water on the roof or the sides of the duct above the roof line. I swear the dang this is possessed.

I still say the water is leaking from somewhere in that cooler. A new cooler is alot cheaper in the long rung compared to constant ceiling repairs.

Right now there is no insulation under the cooler duct. When we had the leak last year we tore out a section of the ceiling and the blown in insulation under the duct. I'm completely stumped by the leaking. When it leaks there is no water on the roof or the sides of the duct above the roof line. I swear the dang this is possessed.

The roof jack that the cooler sits over probably does not go way up into the cooler, the cooler has to have a leak somewhere between the bottom pan and the blower housing and the water is running down the inside of the duct.
If you do decide to replace, consider a single inlet cooler, these coolers have a seperate section where the water is and the blower and duct are in a dry non water area.