A/C Gasket

[TAK14Swift]

Hello all,

Last month during pre trip maintenance I "re-caulked" my roof top AC. Shortly after, I found out that was a mistake! Now, back home with a couple of months of down time, I want to change out the gasket (never been changed) and try to correct the caulk problem. Preliminarily, I found what looks like a small hole in the roof membrane about the diameter of pencil lead under the rear part of the AC.
My questions are:
1. How should I repair the hole? Should I use Dicor self leveling caulk ,Eternabond tape or something else?
2. It seems there is a wide range of AC gaskets. I would like to get one of high quality. I have looked at Steele Rubber (Amazon $ 83). Does anyone have any other recommendations?
3. I also noticed that the rear section of the AC sits directly in contact with roof. Is this normal?
.
The AC is a Coleman Mach(Airxcell 4000 series roof mount). I bought this TT new and have had no AC issues. When not in use, it is kept under a shelter.

As always, any advice, suggestions, or recommendations would be greatly appreciated.

Thank you.

[Jagiven]

The AC sits right on the roof membrane. Some AC's are larger and have an extra piece of foam to help provide additional support to the AC.

If you found a pin hole. How to fix it I would say the fix really depends where it is at.

If this small hole is far enough outside the foam gasket, I would not hesitate to use eternabond. This sounds like your scenario.

If this hole is really close to the gasket, then here are my thoughts.

I really like Eternabond, but I'm not sure I would want to create overlap or butt joint, as the edge of these intersection could allow water to leak past as the foam might not conform to the sharp edge or possible gap. If you could find a large piece of eternbond that was say 16-20 inch square you could place over the opening, and then cut out for the AC, I would like that solution.

Decor, again pending on the location. Maybe with the AC removed. Lift the membrane and apply a little Decor. Then apply a thin layer to the top side of the membrane to seal form a good sea. Once the Decor is dry then apply the new foam gasket and install the AC.

With any solution I would just be nervous about creating a gap that water could leak past.

If you use Eternabond, remeber do not stretch it, or it will release from the roofing membrane within a few days.

[Tunce the traveler]

The gasket kit comes with extra pieces to support the unit. I purchased the kit from a Jayco dealer.

[TAK14Swift]

Thank you for your response Jagiven. I should have been more specific. The hole is not near the gasket so it sounds like Eternabond could be the best solution.

[TAK14Swift]

Tunce
Thanks for the photo. I have yet to pull my AC unit so this is helpful.

[Tunce the traveler]

Originally Posted by TAK14Swift

Tunce
Thanks for the photo. I have yet to pull my AC unit so this is helpful.

It’s an easy pull with one person & what I did was tape the perimeter of the A/C with painters tape ( on the roof ), I used a soft lead pencil, this way when you reinstall it it fits perfectly over the hole and your 4 corner bolts will line up. No additional help is required if you tape the outline and that means only one trip on the roof
BTW I’m on my 3 gasket over 13 years & have owned it for 10

[TAK14Swift]

Originally Posted by Tunce the traveler

It’s an easy pull with one person & what I did was tape the perimeter of the A/C with painters tape ( on the roof ), I used a soft lead pencil, this way when you reinstall it it fits perfectly over the hole and your 4 corner bolts will line up. No additional help is required if you tape the outline and that means only one trip on the roof
BTW I’m on my 3 gasket over 13 years & have owned it for 10

Sounds like a good plan as I'll be doing this by myself. I am sure I have extended my gasket way past it's normal service life.

Thanks

[Tunce the traveler]

One more helpful word of advice as long as you’re going to be using Eternabond tape. Wrap all 4 sides of the roof cutout because just 1 small leak ( as shown in the picture ) will destroy the roof and when you find out it’s too late.
Remember to snug down those 4 bolts ( gently) before the first trip out & after your last trip out for the season.

[Tunce the traveler]

Seeing that we’re talking about water intrusion & you probably have the same window frame as I do there’s another area you should check for a leak. Your door window frame might not be caulked properly and water leaking at this location will destroy your door. I removed my window ( there was no caulk) caulked it and replaced it with tinted safety glass.

[craigav]

Originally Posted by Tunce the traveler

One more helpful word of advice as long as you’re going to be using Eternabond tape. Wrap all 4 sides of the roof cutout because just 1 small leak ( as shown in the picture ) will destroy the roof and when you find out it’s too late.
Remember to snug down those 4 bolts ( gently) before the first trip out & after your last trip out for the season.

Also to note, when I replaced mine last there was a Yellow Tab (one or more) as seen in your photo and the installation instructions stated to tighten the A/C mounting bolts until the "Tab" was flush with the roof top (instead of a particular torque for the bolts). ~CA

[TAK14Swift]

Originally Posted by Tunce the traveler

One more helpful word of advice as long as you’re going to be using Eternabond tape. Wrap all 4 sides of the roof cutout because just 1 small leak ( as shown in the picture ) will destroy the roof and when you find out it’s too late.
Remember to snug down those 4 bolts ( gently) before the first trip out & after your last trip out for the season.

Are you saying wrap the cutout while the AC is pulled?
I can’t tell what it is that you circle in the photo of the cutout.

Thanks

[Tunce the traveler]

Originally Posted by TAK14Swift

Are you saying wrap the cutout while the AC is pulled?
I can’t tell what it is that you circle in the photo of the cutout.

Thanks

If you enlarge it you will see a water stain mark where water started to enter the cutout edge of my roof & if i hadn’t seen it it would have destroyed my roof. And that’s why I suggested that you wrap that edge with Eternabond tape to completely waterproof that open cut

[Grumpy]

Originally Posted by TAK14Swift

Are you saying wrap the cutout while the AC is pulled?
I can’t tell what it is that you circle in the photo of the cutout.

Thanks

Don't have the tape under the gasket...

[Tunce the traveler]

Originally Posted by craigav

Also to note, when I replaced mine last there was a Yellow Tab (one or more) as seen in your photo and the installation instructions stated to tighten the A/C mounting bolts until the "Tab" was flush with the roof top (instead of a particular torque for the bolts). ~CA

When you first install the gasket that yellow tab will be flush with the roof but as the gasket gets tired over time ( say after 1 season) you’ll need to snug those 4 bolts just a tad to prevent that gasket from leaking in one side or the other. My yellow tab shows how much it squeezed down after its 2nd season. Do not compress the gasket just snug a tad each year and you’ll be fine.

[TAK14Swift]

Originally Posted by Tunce the traveler

If you enlarge it you will see a water stain mark where water started to enter the cutout edge of my roof & if i hadn’t seen it it would have destroyed my roof. And that’s why I suggested that you wrap that edge with Eternabond tape to completely waterproof that open cut

I understand now. I plan on pulling my AC this weekend.

Thank you

[TAK14Swift]

I’ve just pulled the AC. There is a small hole where the gasket sits so I may try a little dicor there as mentioned earlier. Thankfully no sign of water intrusion. Biggest challenge is going to be removing the caulk I put on. I’m removing some but it’s a slow process.