Another rooftop ac leak

[NHCelt]

Okay, I have kind of had it with my Dometic Blizzard ac units leaking into my 2016 Bighorn and I need some good advice. They have been through the recall for drain holes, and have also been tightened for rain leaks. Heavy rain last night and another small leak down through the intake vent.

I checked the bolts and 3 appear tight while one seems not to grab anything... Could it be stripped by an overzealous rv mechanic?

I am out of warranty and tired of rv mechanics. I think it may be time to remove and replace the gasket.

Are all gaskets the same, are there bigger and thicker gaskets that are better?

How difficult is the process and how are these new style units bolted to the roof.... And what would be the solution to a stripped bolthole?

Thanks... really want to get this fixed correctly. There have been too many hands up there on my roof that have been unsupervised!

I'm handy enough, but not experienced with ac gaskets, so all info on the process and tips are welcome.

Thanks.

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[NHCelt]

Update. If you have these ac units.... You need to read this.

MY ac units were repaired according the the heartland tsb regarding water intrusion through uncapped and unused mounting holes in the front of the ac unit. What I have just discovered is that theTSB failed to address the two mounting holes in the rear of the unit, both of which also allow rain water to enter the interior if the coach.

After my most recent leak in heavy rain, I opened up both of my ac units. The hardware in the area of these mouting holes show significant corrosion, and the area was clearly wet from the recent rain. You may think that the shroud protects this area, and it would if it was designed differently. But the big issue is that I could use a flashlight inside the fan plenum and see the light clear through the unused hole. I will notify Heartland tomorrow, but this has been an ongoing issue for many and sealing these two holes may resolve the issue.

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[Gary521]

From the picture, your unit was NOT repaired according to the TSB or so it appears. It was not just filling the mounting holes but adding more drain holes. This is perhaps the cause of the corrosion. In addition, The foam cover may not have been replaced properly allowing a lot of rain water to get in.
A while ago several people complained of loose gaskets ( loosely mounted AC units ). I think there are posts that addressed this.

 

[NHCelt]

Gary... The holes were drilled in the front of the ac. This is the rear if the ac. I have the TSB. Nothing was to be done in this area. Note that the open mounting hole is INSIDE of the roof to ac seal.

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[mlpeloquin]

You could also replace the hardware with stainless steel to prevent future rust.

 

[Gary521]

Little hard to tell. I have the same AC. A short time ago, we went thru a brutal night in Florida with 6 in of rain and 40 mph wind. The wind and heavy rain blew the water under the top slide out seal on one side but the AC's did not leak. If rain is getting in, you definitely have other issues.

I also agree that stainless hardware will help.

 

[NHCelt]

Well... For sure those two aft mounting holes should not be inside the gasket and allow water into the plenum. Real hard rain here again today... No leaks. Interesting that the folks on the Montana website had the same issue.

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[NHCelt]

Update... Still not leaking after caulking these aft mounting holes. Hoping it is finally fixed.... Fyi, other Montana owners have found that sealing the top clamshell cover seam with clear waterproof tape also limits excess water.
Hope this helps someone.

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