Roof leak around Airconditioner

[litlgeezer]

Folks,

When the humidity is high and the AC is running, water runs back into my coach. It ponds on forward side of the AC in this area. Some PO evidently knelt down here put in a nasty dent. There is some water coming through the drain hose as it should, but much is coming back into the trailer. I haven't had the AS in rain yet, but I'm sure it would leak a sieve.

How would you recommend I patch this? I would prefer to lift the AC, restore the roof curvature, and seal properly. However, removing the AC would be a difficult one old man job. And, I am still trying to figure out how to remove the folda door header. I don't want to start disassembling bedroom overhead storage units. (I have to remove the header in order to remove the interior AC shroud).

Someone has evidently tried to caulk the crack before. Working on the round, flimsy roof is tricky. Any suggestions will be appreciated.

[Protagonist]

To avoid denting the roof any farther, put a piece of foam down on the roof; one of those eggcrate-pattern matress covers should work. Place a piece of plywood on top of that to distribute your weight over a larger area. The foam should supply a bit of "grip" to the plywood so it doesn't slide as much; test it before trusting your body to it.

Don't make the plywood too big; it shouldn't extend over the curve of the roof at the edges (mainly so you don't flip it like a tiddledywink by stepping on the edge of the plywood where it's unsupported).

Use a putty knife (with rounded corners to avoid scarring the aluminum) to gouge out all of the existing caulking. If you try to caulk over what's already there, there's no chance you'll seal the leak.

Apply new caulking in accordance with manufacturer's instructions. I'll leave it to another Forum member to recommend the right type of caulk. My initial instinct would be polysulfide, available at most boating supply houses such as West Marine, but I honestly don't know how well polysulfide does on aluminum, so I can't recommend it to you.

[Soyboy]

Are you sure that the drain hole in the condensation pan isn't partially clogged? Perhaps allowing some water to drain but other water to build up an leak into the trailer. I had this problem (like many others) I blew fairly low pressure air up the tube and it stopped it (I also cleaned out the pan as best that I could). I blow air up there now at least once or twice a year as preventative measure. I also think the drain pans can crack an cause leaks, perhaps some else will chime in about that, there are threads on here about that problem also.

[Lumatic]

Remove the old caulk and recaulk with Vulkem. Most caulking, other than silicone can be softened up with a heat gun.

[azflycaster]

Unfortunately the design of the AC install only lasted around 35 years on mine as well. The drip pan was attached to the skin and the AC was mounted on top of that. Over the years the weight of the unit caused the outer skin to bend and there is no support between the inner and outer skins.

You can clean it up and reseal, but the outer skin will bend more and leak again. The only way to repair this would be to remove the old unit and install braces between the skins. At that point it would be easier to install a new AC unit.

[A W Warn]

I think you need to remove the AC unit if you really want to "fix" your problems. I had to do this last year. My problem was condensate leaked to the interior even though the drain tube was dripping like it should. The drain pan was cracked.
And reinforcing between the skins can fix that dip in the skin.

[Condoluminum]

You may also need new square gasket seal between A/C and the roof... Ours was compressed and dried out, and source of leaks.. Also not easy 1 person job.. We took it to a shop to replace..

[litlgeezer]

Appreciate all the input so far. I too, believe that lifting the unit up and improving the foundation would be the best option. However, can anyone give me a hint as to how much trouble I am going to have in removing the interior folding door header? Past weekend, I removed two or three screws, but the header was still tightly in place. Will I have to remove the OH storage bin (s) to remove the header (from where the door curtain hangs)? This seems like a lot of useless work, just to remove the interior AC shroud. This is the reason why I am even considering re-caulking between the AC and roof. Seems like all I have done with the AS is work on it, since buying one a year ago. I haven't even gotten to pull it down the road yet

[litlgeezer]

Thanks for your good tips Sir.

[litlgeezer]

Friends,

Just an update to end this thread. Thanks for the several comments / suggestions. After removing the exterior shroud, I took off the upper plastic housing and found the drip pan. After cleaning some small amount of dirt residue from it, I poured water into the pan and it did not drain out anywhere. I removed the water and finally found the drain spouts and the holes that were designed to allow the condensate to enter into a lower metal pan into which the water flows into a drain hose. The pan holes were hard to see. There appeared to be a black thin gasket material that was sandwhiched between the upper and lower pans. This could have been some type of a filtering material, nevertheless, I removed as much of it as possible from inside the drain holes. The pan emptied right out through the drain hose.
This led me to believe that the roof dent was not leaking as it was caulked pretty solidly. It's not pretty, but only truckers might notice it. I decided to leave well enough alone for the time being.
Yesterday, there was high humidity pending a front coming through, so I ran the AC on high for several hours and no drips to the interior. Also, I left the AS in heavy rain overnight and found no leaks at the AC (from the old roof dent). [A few drops from around the door, but I'm thinking a new, thick door gasket might fixed this.]
Special thanks to Soyboy for encouraging me to check out the drip pan for obstructions and to Protagonist for the tip on working on the roof - leave it to a Cajun for a good home remedy!
I hope this comment will help someone else in the future.