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Old 06-02-2022, 05:17 AM   #21
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Quote:
Originally Posted by JohnB View Post

If you are going to pull the AC, let me know and I will explain how to get the old gasket off the bottom of the AC tub and how to install the new gasket and where to buy one.

John
So, I am going to prep to pull the AC off. I would like to know the place you have found to get the best gasket.

Then when you get time, the info on cleaning the old gasket off and any tips on reinstalling.

In regards to the OSB that surrounds the hole and lifts the AC unit higher:
A) if it needs replacing(likely), can I do that from the AC opening?
B) is there any reason I can’t replace the OSB with a plywood. ( I hate OSB).
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Old 06-02-2022, 08:14 AM   #22
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Originally Posted by JimS View Post
So, I am going to prep to pull the AC off. I would like to know the place you have found to get the best gasket.

Then when you get time, the info on cleaning the old gasket off and any tips on reinstalling.

In regards to the OSB that surrounds the hole and lifts the AC unit higher:
A) if it needs replacing(likely), can I do that from the AC opening?
B) is there any reason I can’t replace the OSB with a plywood. ( I hate OSB).
Hi Jim,

Wise choice, hopefully all that spray foam caulk they used will release in some kind of easier fashion.

To get the old gasket off the bottom of the AC unit, they are really stuck on there. The gasket comes with a self adhesive tape on it, and it really bonds well to the bottom of the AC tub. I have tried several ways to get them off, each time the process gets easier but it is still a process. Pending the tools you have to work with here are some ways I have done this.

This link will take you to a post I did on one of my project campers. I did finish the camper, never made it "yet" to finishing the post, but the AC cleaning was the last thing I posted. Lucky you! While the AC was off, I went through the whole thing, tested it on the ground and cleaned it. While yours is older, yours looks very close to the same vintage. I suggest you clean both coils while you have the AC off the roof.

https://www.sunlineclub.com/forums/f...tml#post155094

The link shows me using a flat scraper blade in a vibrating tool. That works well for getting the big chunks of the gasket off. Try not to gig up the tub with the scraper, or you will need to paint the scratched off paint so the tub does not rot out from the bottom up in the future.

Once the big chucks are off, I go in with a heat gun and a all sides dulled up 1" wide metal scraper. The heat softens the adhesive and then the scraper peels most all of it off. If you do not have a heat gun, a hair dryer will work. You only need enough heat to softened it up to scrape off. Do not over heat in one spot or it will burn. You will get the feel for the heat when the gasket starts to come off with the putty knife.

You will be left with a gummy goo and little bits stuck on. You can try mineral spirits if it will cut the goo. Or 3M adhesive remover, the older stuff you can't buy any more. And Goo Gone can work too, it will just take a little soak time and is a lot cheaper then the 3M industrial stuff. You want to end up with the surface totally clean. And it will come clean with the above process.

To install the new gasket, while the AC is still on the ground, you line up the inside of the square hole in the gasket with the witness lines of where the "inside" of the old one came off. I say the inside, as Dometic changed the gasket widths over the years and the outside size changed. The inside has stayed the same. If you want a guide edge, use masking tape on the inside area to show where to line the gasket up. Once you pull the release paper on the gasket, and that gasket touches the tub, it is started to stick and not a lot of any movement can be made.

Also, something to check and make sure yours has these, a prior owner may have nocked them off or they fell off. There are stiff foam support pads on the bottom of the AC unit. These need to be there. When the gasket gets compressed to 1/2" from 1" (the install spec for compression) the pads touch the roof a little before the 1/2" gasket compression. The pads are about 9/16" to no more then 5/8" thick. They are there to help carry the weight of the AC and no over time keep squashing the AC gasket bouncing done the road. Most all AC units had 4 pads at the gasket corners, others had 6 pads, 2 where more under the compressor end but there has to be roof support to line up with them. Like the next rafter under the AC unit. If those 4 to 6 pads are gone, I have made them out of pink closed cell insulation board used on the sides of foundations etc. They can take the load, the weather and you can cut them with a saw. Then I used double sided taped to hold the 4 main ones in place until the main gasket was compressed. The last 2 by the compressor, I custom fit the thickness and slide them under to line up with a rafter after the AC unit it mounted. The are also double side taped to the bottom. Lift the AC up a little, slide them in, then put it back down.

Here are the 4 white pads shown my the AC gasket. You have to have these 4. There were 2 other pads that fell off out under the compressor, the brownish squares are the old self adhesive in this pic when we where removing the AC.


You can see the touch down of the 4 pads on the roof. This is a rubber roof where the prior owner did not do much cleaning and they get yucky under the AC anyway. You cannot see the 2 pad marks under the compressor area as they fell off along the way.


These links have some more pics from other campers with the AC change out. They may help. I think I need one post on just changing the AC unit.

scroll down the pics will come to a AC unit
https://www.sunlineclub.com/forums/f...tml#post132017

https://www.sunlineclub.com/forums/f...ics-17066.html

A tip, once the new gasket goes on, you cannot slide the AC along a surface. You have to lift the AC up and move it, or it can damage the new gasket sliding it.

Where to get the gasket, you are looking for "Dometic 3310718.006 Air Conditioner Mounting Gasket - 14" x 14""

I have bought from these folks with good success.

I know this supply house, they are local here in OH. They sell from their website, and on Ebay. They have free freight. They sell on Ebay cheaper then their onw site, not sure why.

There Ebay site, https://www.ebay.com/itm/272608795939

Their main web site https://www.boatandrvaccessories.com...ket-3310718006

On Amazon I bought several from this dealer in the past. https://www.amazon.com/gp/product/B0...sc_act_title_1

The prices are all over the map right now. And doubled due to Covid issues. You can search for that Dometic part number, even try a local RV dealer.

The OSB board, I agree, I hate it too... You can use 1/2" plywood no problem. The OSB in there now is most likely swelled even if it is not rotted. You might have to shim any new 1/2" plywood up to make it even with the rest of the older OSB . Here is what the AC unit wood may look like. This is a newer Sunline, but I suspect they did similar on your on one.

The AC hole is in the middle of the pic, there are 4, 1/2" x about 4" wide pieces stapled to the top of the rafters.


You should be able to lift the metal up and see that pad if it is intact. Most likely they stapled the OAB pad to the rafter. If you have to take it out to replace, pry it up with a bar and try and shear off the staples as you may not have enough roof to lift it straight up and off with the metal roof on.

Hope this helps

John
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Old 06-02-2022, 08:53 AM   #23
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You can see how far the old caulk went. I don’t think I needed to put that much down. And yes I now see what you mean by the dimples! Why would a company think that’s a good idea. To shed water you want smooth.

Wish the pictures weren’t so fuzzy.

Attachment 8782

Then experimented with a short run on the edge. It was turning out great until I got forgetful and placed my hand on it….yikes, what a mess that became. Looking at it now, I see a few spots that aren’t right. I need to practice. I feel I will be getting plenty of practice!
Attachment 8783

And while these two photos are here, the roof looks like it was, or is, white. When cleaning the areas, it comes off. Is it a good idea to paint it when all done?

I forgot to answer the question on the roof paint. I would say, do not paint the roof "before" you are done doing all the Ebonding or caulking. This allows you to clean the base metal totally with no new paint in the mix. The bond of the caulk and Ebond will be to the metal direct.

As far as painting for long term. That is a good question. I have never done this on a metal camper roof. I would for sure wait until all the roof and camper restoration work is done before painting it so any caulk etc. bonding is before the paint. And if I were to paint it, it would be oil based paint, primed to deal with bonding to the aluminum and equipment/pro grade to better handle the outside weather all the time.

I have seen/worked on year 2000 aluminum metal roof campers that had no paint at all originally. And it still has no paint. It's my neighbors Coachmen camper. As long as there is not a corrosion reaction the bare aluminum appears to be holding up. I know Sunline had painted many of them, but I think that came baked on with the metal from the supplier. It was not painted on at the factory.

I would say it's your call on this one. For sure you do not have to paint it now to help stop leaks. It's more of a lasting thing for the next 29 years of your campers life...

We do have a club member painting the siding on his truck camper rebuild and others have painted the siding on their campers. So the paint is not an unheard of thing to do. I myself have even painted damaged siding, just not a metal Sunline roof.

Hope this helps

John
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Old 06-09-2022, 07:03 AM   #24
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I have begun to remove the AC. I am wondering if there would be any bad results if I would put a thicker board around the 14 x 14 hole? Take away the OSB piece and put something like a a 1” piece to raise it up another 1/2”. I imagine that would then require thicker foam pieces for the outside support pads. Would the bolts that pull the AC tight to the roof be long enough? Thoughts? Anybody else do this?
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Old 06-09-2022, 07:29 AM   #25
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Hi Jim,

If you find you have to raise the AC to help get out of the ponding, the idea is not a bad idea and may help. The only thoughts though is how high to raise it? Going up an extra 1/2" above factory may make it or not. You will have to try and see. 1/4" you may not find it, 1/2" you might. The metal will have to accommodate the lift and flex/bend from the main roof line to the new higher pad. That may be more of your issue, dealing with that transition, especially are the seam which is a lot stiffer. Sunline does this lift up on the rubber roofs all the time but the rubber is more tolerant to elevation changes where the metal may not be as much.

You will have to make a judgment call when you can see what you have to work with. If the rafter sunk 1/2" on one side, then raising only that side 1/2" extra may not be an issue. You would have to shim blend in different thicknesses most likely to create a flat surface as the other side may not need any extra lift.

The bolts themselves should be plenty long enough to get them started, again pending how high you lift up the AC, and extra 1/2" may not be a problem. The 1" tall gasket is to be compressed to 1/2" so there is always more bolt thread once you get it started.

Here is a thought, pending what you run into, if you have ponding due to bent down metal near the AC area, if you have some 1/8" or 3/16" (nominal 1/4") plywood sheets, shove the sheet under the sunken metal to lift it up and give full time support. The plywood would have to span 2 rafters and ideally you use weather rated construction adhesive or flat head screw the sheet in place to not move on the rafter. I have had to do this on the rubber roof Sunline system when someone stepped in-between the rafters and broke the budboard (thick corrugate backing) and that foot in the wrong place cracked the backer board and left a deep sunken spot to collect water and not drain.

Your metal roof may be a bit harder to lift up, and installing screws in the plywood may not happen, but good weather rated construction adhesive to the plywood and the rafter may work and need less room to get in there. The metal would be free to move, I would not put adhesive on the metal membrane.

Good luck on this adventure and let us know how it comes out.

John

PS. You may not/would not, have to change the lift pad thickness. The AC gasket is still going to compress the same amount regardless of the wood shim under the roof membrane. Think about that.
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Old 06-09-2022, 09:58 AM   #26
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In regards to the pad thickness: I think they would be thicker.
Yes the foam will compress to 1/2”. If I raise it 1/2” more at the 14x14 hole, that’s where the gasket rests on. So, the AC will now be 1” higher, but I did not raise the rafter areas where those pads will rest. The metal roof may be pulled up slightly from raising it a foot away(at the gasket area). But the support for those pads would now be lower in relation to the AC wood frame.
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Old 06-09-2022, 11:18 AM   #27
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In regards to the pad thickness: I think they would be thicker.
Yes the foam will compress to 1/2”. If I raise it 1/2” more at the 14x14 hole, that’s where the gasket rests on. So, the AC will now be 1” higher, but I did not raise the rafter areas where those pads will rest. The metal roof may be pulled up slightly from raising it a foot away(at the gasket area). But the support for those pads would now be lower in relation to the AC wood frame.
H'mm, well, it sort of depends. I'm not sure I follow exactly how you are adding this new higher riser pad, how wide it is and where it is above or below the metal membrane. I assumed it was below the metal roofing membrane.

The newer Sunline camper 1/2" thick more standard riser pad was about 4" wide beyond the ID of 14 x 14 opening. The gasket is about 1" wide, that leaves 3" more wood riser pad exposed that was "under" the roof membrane at the 14 x 14 opening. The 4" wide wood riser pad at the gasket area supports the foam support pads resting on the top of the metal membrane in the 3" wide area beyond the gasket under the metal membrane. On top of the membrane the closed cell foam pads where about 9/16" to maybe 5/8" tall, They would compress to the same 1/2" compressed gasket height.

The 2 other support foam pads under the compressor, that might land on a rafter, get custom fit to fill the space after the compressed AC gasket is in place. The roof is never flat enough to predict this exact thickness. Or hasn't on the roof AC units I installed.

If you are adding your new riser pad "on top" of the metal roofing at the 14 x 14 opening, are you? and the new riser pad is the same outer perimeter size as the AC gasket, then yes, the 4 foam support pads need to be increased to add the thickness of what ever you added. The other 2 at the compressor are whatever they need to be to fill the space.

If you are thinking about lifting the AC "above the metal roof" with a riser pad, it should be sealed to the top of the metal metal roof and ideally be made out of something that will not be water affected, like a UHMW or other plastic or metal wrapped something.

With all that said.... LOL how are you thinking of adding this extra riser pad? Do the 4 closed cell foam support pads at the AC gasket area touch the roof metal at the same plane as the rubber AC gasket does?
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Old 06-09-2022, 11:42 AM   #28
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I’ll get back to you on the riser.

New discovery. Notice the holes around the perimeter of the opening? The gasket center will be over these. Is that enough to keep the water from getting to the holes? I’m doubtful.

Each hole has a raised perimeter as metal gets when a hole is put thru. I was going to grind of each point as it being abrasive on anything sitting on it. However a raised edge around the hole is also a slight curb for water from getting in . Hmmmm?

- Jim
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Old 06-09-2022, 07:18 PM   #29
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I’ll get back to you on the riser.

New discovery. Notice the holes around the perimeter of the opening? The gasket center will be over these. Is that enough to keep the water from getting to the holes? I’m doubtful.

Each hole has a raised perimeter as metal gets when a hole is put thru. I was going to grind of each point as it being abrasive on anything sitting on it. However a raised edge around the hole is also a slight curb for water from getting in . Hmmmm?

- Jim
Jim,

OK, I know what you are looking at. There used to be a crank up roof vent in that roof AC unit location. Some prior owner removed the crank up vent and installed the AC unit. Some of the older campers were even wired for an AC if it was not ordered from the factory as back then, AC's where an option and not a standard install like the newer ones are.

Not what to do with the holes. Here is what I would do, it's not the only way, consider it an option you can build on.

Using a ball peen hammer, hold the ball on the top of the pulled up metal, then hit the hammer head with another hammer to peen down those rough edges. Flip the hammer to the flat side and hit too if needed. This gives you a more flat surface then the metal sticking up volcanoes. I did this method with the 2 hammers to not miss and make more dents in the metal. If you do not have a ball peen hammer, use a normal hammer and try and not miss the mark.

To make a better sealing surface then letting the AC gasket seal the holes, I would apply 2" wide or wider if that is what you have, Eternabond roof seal or the Eternbond Alumni bond around the 4 sides. This seals over the holes and helps fill in the dimples. The AC gasket will seal well to the TPO top of the roof seal or the smooth aluminum top of the Alumni bond. I would run a small bead of Dicor and smooth it out (wet soapy finger) on the exposed outside edge of the Eternabond so dirt does not stick to it over time. I would not Dicor treat the inside perimeter of the Ebond as this is not exposed to the outside world. This method of Ebonding the area lets you install the Ebond just before setting the roof AC unit on top if wanted. No cure time needed. The Dicor will cure in time but there is no AC gasket over the wet Dicor.

The use of the Eternabond is personal choice. I would use it without hesitation as I have used so much of it over the years and I cannot see any down sides, only upsides from using it. That said, I'm sure there are many AC units out there on the older metal roof campers that were added that they used the gasket over the top of the holes. As long as the AC platform is the highest point on the roof, then water should always wick/shed away from the gasket. But, things do happen, best is to deal with the holes in some fashion.

If you have no Eternabond, you can use the Dicor caulk you have smoothed out over the holes a day before you install the roof AC unit. For sure wait at least overnight enough for the Dicor to cure up enough before setting the AC on top.

Hope this helps.

The good news, you have the AC unit off the pad and the roof cleaned up. Yeh!. You are off to a good start.

John
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Old 06-09-2022, 09:19 PM   #30
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Since the holes are there, I was thinking about opening a few of them larger. This would allow me to run some screws into the new riser frame. Then after that’s installed, follow thru with sealing as you described.

Without opening up a few holes, I just don’t know if I can get a screw angled downward enough and catch the truss framing in a secure enough way, if I do it from the edge. Don’t know if that makes sense to you. I suppose I could glue the riser pad to the trusses, but rather not for fear of having to work on it at again some other day.

I have also thought about driving regular nails that would fit thru the current holes, but Leary of pounding so hard on the trusses to get them in. That might tear apart the already weakens ceiling panels.

You know, I’ll have to look at it tomorrow. Right now I’m thinking I could modify a few screws by grinding their heads smaller yo fit thru the holes.

Lots more to share, but it will all have to wait for now.
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Old 06-09-2022, 10:16 PM   #31
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Since the holes are there, I was thinking about opening a few of them larger. This would allow me to run some screws into the new riser frame. Then after that’s installed, follow thru with sealing as you described.

Without opening up a few holes, I just don’t know if I can get a screw angled downward enough and catch the truss framing in a secure enough way, if I do it from the edge. Don’t know if that makes sense to you. I suppose I could glue the riser pad to the trusses, but rather not for fear of having to work on it at again some other day.

I have also thought about driving regular nails that would fit thru the current holes, but Leary of pounding so hard on the trusses to get them in. That might tear apart the already weakens ceiling panels.

You know, I’ll have to look at it tomorrow. Right now I’m thinking I could modify a few screws by grinding their heads smaller yo fit thru the holes.

Lots more to share, but it will all have to wait for now.
Hi Jim,

I would not use the nails, they can back out over time and as you said, the pounding on the truss is not good.

They do make thin head screws. I use then sometimes. They call them Sharp point lath screws. Teks is one brand. See here, while you may not have Menards near you, other building stores may have them or simalar
https://www.menards.com/main/hardwar...976207&ipos=10

The larger head will work well over the metal and you do have have to open the hole up. Sunline uses no 8 screws on the roof vents, so your holes are most likely from a no. 8 screw. Have a look and see if these will work for you.
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Old 06-10-2022, 04:45 AM   #32
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Oh, so you are proposing to pull the metal down against the riser frame, and the screw heads on top. I was thinking of not securing the metal and letting it float on the frame like it has been with screw heads underneath the metal and flush with wood surface.

Pros and cons to each scenario I guess.
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Old 06-10-2022, 05:47 AM   #33
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Since the holes are there, I was thinking about opening a few of them larger. This would allow me to run some screws into the new riser frame. Then after that’s installed, follow thru with sealing as you described.

Without opening up a few holes, I just don’t know if I can get a screw angled downward enough and catch the truss framing in a secure enough way, if I do it from the edge. Don’t know if that makes sense to you. I suppose I could glue the riser pad to the trusses, but rather not for fear of having to work on it at again some other day.

I have also thought about driving regular nails that would fit thru the current holes, but Leary of pounding so hard on the trusses to get them in. That might tear apart the already weakens ceiling panels.

You know, I’ll have to look at it tomorrow. Right now I’m thinking I could modify a few screws by grinding their heads smaller yo fit thru the holes.

Lots more to share, but it will all have to wait for now.
Hi Jim,

Wow... amazing I read your response and never came up with you were thinking of the screws under the metal. I could not figure out why you wanted to open the holes up. Now I know.

Quote:
Originally Posted by JimS View Post
Oh, so you are proposing to pull the metal down against the riser frame, and the screw heads on top. I was thinking of not securing the metal and letting it float on the frame like it has been with screw heads underneath the metal and flush with wood surface.

Pros and cons to each scenario I guess.

OK some quick thoughts. If you want very little to no heads on "top" of the metal, try a no. 8 flat head screw after your pound the metal flat. Try one with no counter sinking. The screw may swedge the metal down into the wood and be closer to flush on the metal. Or if it does not sink on it's own, then slightly countersink the metal and wood and it will set deeper.

If you are going to use the Eternabond over the area, it will seal off any holes or screws as long as they are close to flat with the surface.

As for the metal floating, may be overthinking this. Every roof flange up there, tank vents, fridge vents, including the old crank up roof vent was screwed down to the opening. There was no float to the metal.

Normally on the rubber roofs, the roof membrane at the AC hole has a fastening to the inside of the 14 x 14 hole. It helps stop the membrane from sinking and pulling on the gasket. In your metal roof case, if the metal is fastened at the 14 x 14 opening, the metal will not want to slightly sink with snow load or other light loads on the roof which would pull on the gasket as the roof sinks.

In all reality, it may not matter if it floats or not. The gasket squeeze is so great it creates a big clamp on the metal to the roof wood. Yes, it is only a friction clamp, but still a form of clamp.

Think through which you feel will seal best, a floating metal or a fastened metal? Again, I think either will work with the fastened being a little better.

Good luck today, I'm off to help my son with his house roof...

John
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Old 06-10-2022, 06:15 PM   #34
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Ok, back to the pads that go between the AC and the metal roof. The photo below shows the areas where the pads had been. The one in the bottom left corner of the photo is barely noticeable, but one had been there. There were six all together. There was only one pad still intact when the AC was removed. The others had been gone.


70026B98-B85C-4CF6-87F0-2DF5AAA80883.jpg

After removing the OSB riser boards under the metal roof, I put them onto the base of the AC to see where the pads were in relation to the riser boards. As you can see, the one pad was not over the support riser. I will move that one to the right location when installing the AC again. And John is right as to the support pads directly around the 14 x 14 hole don’t need to be increased when making the risers taller, if they are on the riser.

41831F07-BBD9-4C12-9A4D-5A1B87DE253C.jpg

However, of the total of the six pads there are two that are near the back end of the AC . These pads will need to be increased to accommodate the new riser height. How much, I don’t know yet. I think the only way for me to know is to place the AC in it’s spot with the four pads around the main hole, and then see what space is left in the back areas. I suspect that it will be different from right and left sides.
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Old 06-10-2022, 08:41 PM   #35
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Originally Posted by JimS View Post
However, of the total of the six pads there are two that are near the back end of the AC . These pads will need to be increased to accommodate the new riser height. How much, I don’t know yet. I think the only way for me to know is to place the AC in it’s spot with the four pads around the main hole, and then see what space is left in the back areas. I suspect that it will be different from right and left sides.

Hi Jim,

You are doing great work!

I can see what looks like water staining on the OSB board. At one time, there was a leak there. Not sure of when, before or after the prior owner tried to caulk the gasket.

On the pads, the two pads that are out by themselves, you are correct, those will have to be custom thickness pads. Once you install the AC unit, tighten down the 4 bolts, the 4 pads that where premade in thickness, should be touching and helping support the AC weight. The AC gasket is looking for approximately 50%compression, from 1" thick new uninstalled, down towards approximately 1/2". I use the wording approximately as the roof is corrugated metal, and then the roof is not made dead perfect even when new. You may be able to get real close to having all 4 sides compressed close to 1/2", or one area may be a little more or less, meaning about +/- 1/32" to 1/16" in one area, but the other 3 sides are closer to the 50% compression.

That then declares the compressed state of the AC unit on the new gasket. It will work well like that, even is it is not dead perfect on all 4 sides as you can see inside the camper.

Then, you deal with the thickness of the last 2 pads, even if you use a riser board or not, odds are high those 2 pads will be different thickness from the center 4, pads. And the left and right side pad can be different from each other. How I determine those thickness is:

First, find a location where there is support under the roof metal membrane. near the 2 rear pad area.

Measure the space at the pad location with the AC installed and tightened, add approx. 1/16" to the space you just measured. Note: Account for the thickness of the any double sided tape you use to hold them in place.

You will create a new custom thickness pad to fill that location. Lift the AC up slight at that corner, push the pad in place and let AC back down. It will move the 1/16" up to allow this. It is not that rigid.

I use outside weather rated 3M double sided tape on the pad to get it to stick to the bottom of the AC pan. You may have to account for the 3M tape thickness in the over all height of the new pad and decrease the pad accordingly. The brand you buy may be different then the one I use, so I cannot tell you how much to reduce the pad by. It's not much.

Then do the other side pad the same custom thickness.

A main thing on the location of those 2 pads, they have to actually touch a location on the roof that has some level of wood support under the roof metal. Check what was there, they may or may not had any support under those locations. It may be part of why they fell out if they are only on the metal with nothing under them.

I have seen some AC's not have those 2 extra pads, the AC may droop backwards also due to over time. And or the 2 pads fell out. It is not a great setup, but it has worked. Ideally there is some kind of support under that pad location. Move the pad as needed to reach the support. They do not have to be in the same place as they were originally.

You are doing great, keep up the good work. Good job on cleaning up the old gasket that was stuck onto the bottom of the AC tub.

John
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Old 06-11-2022, 05:53 AM   #36
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Here’s a few pictures of the AC removal. As mentioned earlier, the gasket had been set down on a layer of caulk/Dicor making the entire thing glued together without out any easy removal.

02B6C713-A155-4889-A575-ED52F2F47883.jpg

I used a long bladed knife to slice thru the gasket material. I needed to do it from inside as the gasket couldn’t be reached from the outside, it’s too far under. The weight of the AC unit on the gasket applied pressure on the cutting action, making it impossible. So from the top side, I had to shim up the AC unit to get a pulling action on the metal roof. Then as the knife cut thru it would start to pull apart.

14FCE601-BA70-4896-8B8D-2AB4F459D773.jpg

After it was all done, there were inevitable scars on the bottom of the AC tub. After the old gasket was cleaned off, I decided to give it a quick paint job.

51512316-F27A-4407-ABD6-507EFC4ACA53.jpg

John, you are absolutely right about getting that old gasket off. What a messy glue that is. I tried everything you suggested. Some things worked a little better than others. What seems to happen is the solvents loosen up the glue just enough to moved it around from surface to surface, but it never fully dissolves the old glue. You wipe it with a fully soaked solvent rag and some comes up onto the rag. If you touch that rag to another area, the glue gets smeared back down onto somewhere else you don’t want. I even tried many different things that you hadn’t mentioned.

What I found to work the best, right or wrong is debatable, is gasoline. It seemed to cut thru it quicker and leave it a bit more non sticky. I would use a paper towel to wipe on and when some would lift , fold to a new side of the towel. Never apply a dirty towel to an area. I used a whole roll of paper towels, but it got done quickly. Also keep in mind I was going to paint this from prior damage, so I didnt have much to lose. It was actually a chainsaw gas mix. I’m wondering if the slight amount of oil in the gas cuts down on the “sticky” to make it more manageable. Just some random crazy thoughts here…

Of course, after that was done, had to go over everything with a proper cleaner.
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Old 06-12-2022, 05:33 AM   #37
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Upon taking the AC unit off, I found this at the rear end.

F64AFE54-8B2A-4AE0-9DAF-E38284F78E1B.jpg

A bolt head has worn thru the metal roof.

CBF47B80-C890-45E3-94E4-55582CD9561C.jpg

Looking at the bottom of the AC unit, you can see where the pad had disappeared, leaving the roof and AC unit with a place to rub together.

39C2EB6E-D7C5-451E-95BE-953D40D967D7.jpg

When I first started looking at the roof and where it might be leaking, it was suspicious that I could see no gap between the two. Being a newbie to RVs, I didn’t know how the construction of it was suppose to be. So, for those new owners out there, you might want to give this a look over when you inspect your roof. Possibly get a pad/spacer under there if it’s gone?

Pic below is peeking under the metal roof with the light coming thru the hole.

2F51D1C3-9422-4FD5-B873-BE277BD7D9AC.jpg
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Old 06-12-2022, 08:43 AM   #38
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Hi Jim,

You did a great job on cleaning up the bottom of the AC pan. Looks good.

I must say, you win for maybe the hardest AC gasket to get off the roof contest.

I haven't had to cut the gasket in half to get to break free from the camper, at least yet anyway.

The hole from the rubbing screw head, good find. That is a guaranteed leak. You may have had two things working against you in this case. First, the two rear pads were missing and second, the prior owner over compressed the gasket thinking more squeeze might stop a leak. As seen, over compression is not going to help the seal, and worse, it lowers the AC unit allowing the screw heads on the bottom of the pan to get closer to the roof.

In case you have not thought of how to deal with the hole yet, this is where Eternabond comes in, again. Clean the surface and apply a patch on the roof top. I would go for a good 1 1/2" to 2" on all sides of the hole with the pebbled metal surface.

And, if you can reach inside under the metal to the hole area, put a patch on the bottom up also. The top down will work, the bottom up is added insurance for little cost if you can reach that area.

Keep up the good work! Thanks for sharing.

John
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Old 06-12-2022, 04:20 PM   #39
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Yeah, when I saw that hole I was happy that I decided to pull the AC. I’m thinking there’s a 50 % chance that’s the problem. The other being the low spot where the seam is.

Here’s a peak at the support rail that runs back from the AC. The OSB AC riser pads are removed to be able to see this. The below photo is the one on drivers side looking towards the bumper. Looks like it’s still intact.

60A571E2-E545-4A96-A9C8-E0EEC44B1FA5.jpg



This next photo is on the passenger side looking towards the back bumber. It obviously gave out. This is where the depression is on the top of the roof. I am shocked at how little support there is here. Maybe 1/2” thick x 1” wide OSB strip.

1BE638BF-5416-437C-B0E9-C3908CA3E829.jpg
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Old 06-12-2022, 04:45 PM   #40
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Maybe that OSB strip was never meant for an AC. As you pointed out John, there was just a roof vent there and an AC installed later. The serial number on the AC indicates it’s after the year 2000. Camper is a ‘93. The back of the AC unit doesn’t reach all the way back to the next truss. It’s about 5” short of it. So the OSB strip is holding all the weight. Not good. I’m fixing that problem, more photos on this later.
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