A/C unit mounting gasket

[ET156]

I just fond out from a dealer that the a/c mounting gasket needs to be check yearly. There are four bolts that hold the a/c frame and gasket around the roof opening and if these bolts are not tight enough the gasket will leak as mine did. It rained one day and I had a leak at the top of my rear window, I thought it was the window so I taped some plastic over the top of the window out side. well that did not help so I check the rest of my rig knowing water does travel , no luck. contacted my dealer and he had the answer. I checked the a/c gasket and now no more leak. last night it rained really heavy and no leak. this will be on my yearly to do list.

[mhs4771]

My understanding in regard to the AC Gasket is that it needs to be snug but not overly tight. If too tight will deform the gasket and cause a leak.
Now I could be all wet, but that's what I have picked up from other RV Forums.

[ET156]

mhs4771 you are correct too tight and gasket will be damaged

[shrode]

I want to check the AC mounting gasket seal on my 2017 31SL. I've look at it a few times and don't see the mounting bolts that hold the a/c frame and gasket to the roof opening. Everything on line show access from inside the RV for non-ducted installations. Any pictures would be a big help.

[Goat]

I asked a tech, and was told they are held down with lag bolts. One must take remove the top cover to access the bolts.

[Lloyd]

To access the bolts holding the AC unit on out trailer, you simply pop the trim ring off from around the AC unit (inside on the ceiling). There is 4 bolts holding the unit to the ceiling/roof. Check them for being loose. Remember slightly snug, not tight.

[shrode]

Originally Posted by Lloyd

To access the bolts holding the AC unit on out trailer, you simply pop the trim ring off from around the AC unit (inside on the ceiling). There is 4 bolts holding the unit to the ceiling/roof. Check them for being loose. Remember slightly snug, not tight.

The AC air flow on a Redwood is ducted, so there is no trim ring or access to the unit inside the trailer. It has to be mounted from the outside top, but it's not readily obvious where the mounting bolts are. There are a couple of dabs of self leveling sealant at the front of the AC on the roof, but I don't want to peel them up if they're not what I'm looking for. I don't see any mounting bolts at the front or the back inside the unit with the cover removed, and don't want to unnecessarily start taking it further apart if I don't need to.

[XCMARK]

If you remove the lag bolts replace the seal. Disturbing it most likely will cause a leak if you don't have one. I owned a holiday rambler for 10 years never touched the seal/AC unit. If your doing a spring roof inspection I just stick to checking the self leveling seam sealer and cleaning the roof. If you need to lift the AC unit you will need a helper and a half sheet of plywood to put the AC unit off to the side, It weights roughly 130 lbs.

[shrode]

Originally Posted by XCMARK

If you remove the lag bolts replace the seal. Disturbing it most likely will cause a leak if you don't have one. I owned a holiday rambler for 10 years never touched the seal/AC unit. If your doing a spring roof inspection I just stick to checking the self leveling seam sealer and cleaning the roof. If you need to lift the AC unit you will need a helper and a half sheet of plywood to put the AC unit off to the side, It weights roughly 130 lbs.

Agreed. I just want to verify the compression on the seal. It looks like one of those areas where a leak could cause a lot of damage before you even know you have one.

[Lloyd]

Originally Posted by shrode

The AC air flow on a Redwood is ducted, so there is no trim ring or access to the unit inside the trailer. It has to be mounted from the outside top, but it's not readily obvious where the mounting bolts are. There are a couple of dabs of self leveling sealant at the front of the AC on the roof, but I don't want to peel them up if they're not what I'm looking for. I don't see any mounting bolts at the front or the back inside the unit with the cover removed, and don't want to unnecessarily start taking it further apart if I don't need to.

The AC on my trailer is ducted also. Even tho it's not a Redwood. I have to admit I'm not that familiar with RW. I just figured all AC units protruded thru the ceiling. Is that not the case on RW.

[r time soon]

The Redwoods use a return duct system that is closer to the crown moulding at the edge of the ceiling rather than directly below like your picture. The way yours bolts tight is from the bottom through a metal frame below the ceiling. Redwood a/c units bolt down from the top and the bolts get covered with seal to prevent the bolts from allowing the water to flow into the ceiling. The exterior shell or cover then covers it all up. Using the returns makes for a much quieter interior.

[Lloyd]

Thank you for the reply. I learned something today that I was unaware of.

[XCMARK]

typically the AC gaskets are black urethane foam and about 2" tall uncompressed. They get compressed about 3/4" with just the weight of the unit sitting on it. When its pulled down to the roof with the lag bolts it is 1/2" - 3/4" tall on the crown of the roof and more of a gap given the curve of the roof to the outside edges of the AC unit. If a seal is install correctly the first time there should be no need to check it for 5+ years. I would expect at the time of roof replacement it must be replaced or a AC unit repair/replacement . It really is one of the very few areas on a RV I would consider trouble free.

[ET156]

I had to remove a/c lag bolts and nylon spacers. The original spacers where too big so there wasn't any way to tighten the lag bolts enough to put enough pressure on the gasket to keep it from leaking. SO I cut the nylon spacers down and reinstalled I also added a bead of 100% silicon under the gasket. now no leaks. no water damage.