Roof leak from air conditioner?

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Roof leak from air conditioner?

November 12, 2024, 03:40:14 pm

I have a small drip coming through the roof air conditioner. When raining, not when the unit is running. I’ve removed the upper and lower covers from the unit. I cannot see anything from the top down. The caulking is under the unit, not accessible. When I removed the lower cover I saw 3 bolts going up into the unit. Another forum post referenced tightening the bolts for possible leak resolution. Is the nut on the other end accessible somehow? Or does it not have to be? I was able to tighten them a bit, but was hesitant to tighten too much because of the plastic between the bolt head and ceiling. I’m sincerely hoping the unit does not have to be removed and recaulked. It’s coming into winter here in Wisconsin. Thanks as always. Mary

Re: Roof leak from air conditioner?

Reply #1 – November 12, 2024, 06:13:28 pm

The “nut” on the end of the hold down bolts is fixed and does not need a wrench. The Gasket is glued to the roof and very unlikely to leak, regardless of bolt tension.

I would start by putting water in Lake Newton on a non rainy day and see if you get the drip. If not then the leak has to be through the cover or vents onto the base plate and down. I would then remove the cover, put water on the baseplate, and see how it is getting to the interior.

Just some ideas.

Maybe put a cover over the A/C and see if there is a drip if you don’t find a leak through the gasket. The leak is unlikely to be through the the gasket but it is possible.

Re: Roof leak from air conditioner?

Reply #2 – November 12, 2024, 08:23:46 pm

The three bolts, under the interior cover can be tightened until snug. This is probably not the cause of the leak but it doesn't hurt to check. The gasket does compress over time.

The roof A/C sits at the bottom of the depression known as Lake Newton. Any roof leak in the vicinity of the A/C will drain to and come out of the A/C's interior cover. The tiniest of holes can allow water to enter.
It's time to visit the roof again for a detailed inspection.

Larry

Re: Roof leak from air conditioner?

Reply #3 – November 13, 2024, 07:07:54 am

Quote from: Larry W - November 12, 2024, 08:23:46 pm

The three bolts, under the interior cover can be tightened until snug. This is probably not the cause of the leak but it doesn't hurt to check. The gasket does compress over time.

Larry

Tightening the bolts worked for me, the third time was the charm. I didn't want to overdue it so I tightened them a little and waited, it happened again, so tightened some more, etc.

Re: Roof leak from air conditioner?

Reply #4 – November 14, 2024, 09:53:58 am

Further inspection up on the roof shows no obvious area of caulk failure, or leak, anywhere near the AC. Tightening the 3 bolts has not helped. Unfortunately, I can’t examine under the unit, darn. I raised the front of the rv 3” to allow Lake Newton to drain. It rained last night. Leak still coming in left front corner, but now water is traveling along the baseplate to the rear. It seems to be a very small drip. I’m researching service facilities to remove AC unit.

Re: Roof leak from air conditioner?

Reply #5 – November 14, 2024, 03:52:24 pm

Removing the A/C is not a trivial thing on an LD. It is glued down. You remove the three bolts and using wood blocks to protect the roof from your crow bar you gently pry it up. That is the way I did it. If you can, do it yourself. It is a multi hour operation and at standard shop rates you may be looking at $500 just to get it loose. The experience of others is welcome here.

Just an opinion. It is possible yours is not glued down; It has happened. Unbolt it and see if it comes loose.

It took me a couple of days, a trip to the hardware store for a large crow bar, and lots of belly scratching time to get it loose. If your RV service person has not removed one from an LD he knows no more than you do. Why pay him $150/hr to figure it out.

Again, just an opinion. You will need to replace the thick foam gasket so you may as well go ahead and get one before you start.

Re: Roof leak from air conditioner?

Reply #6 – November 14, 2024, 03:59:02 pm

On further thought remove the three bolts, take the face plate off, and see if you can spot the leak. Just guessing.

Re: Roof leak from air conditioner?

Reply #7 – November 14, 2024, 06:19:16 pm

Quote

Removing the A/C is not a trivial thing on an LD. It is glued down.

Man, you can say that again! I was hurling a lot of curses at those LD boys for the ridiculous decision to glue that baby down. I had the same experience as HB. Took me hours to get that thing loose.

In my experience, the common leaking points are plugged drains in the A/C pan (not likely to be leaking this time of year) and a failed gasket. Good luck.
jor

Re: Roof leak from air conditioner?

Reply #8 – November 15, 2024, 03:15:08 am

I never thought of doing from the inside. I did it from the outside requiring great care to not dent or damage the roof.

Re: Roof leak from air conditioner?

Reply #9 – November 15, 2024, 07:15:28 am

Glued in,
Ooops, I just ordered a new RecPro. Maybe I should have repaired my old one and dealt with the noise.

Re: Roof leak from air conditioner?

Reply #10 – November 19, 2024, 03:00:01 pm

Quote from: mrystock - November 12, 2024, 03:40:14 pm

I have a small drip coming through the roof air conditioner. When raining,

Mary

Any progress in finding the leak?
Inquiring minds need to know.

Larry

Re: Roof leak from air conditioner?

Reply #11 – November 19, 2024, 05:45:54 pm

Unfortunately, no solution, yet. I’ve tightened and tightened the 3 bolts for the gasket. I’ve been up on the roof scrubbing and inspecting. I’ve removed the roof cover from the unit and can not see anything from that vantage point. I’ve recaulked the solar panel brackets, JIC. There is nothing mounted nearby except the solar panel. I’ve raised the front of the rig up to promote runoff to the rear. Tomorrow, I’m going to raise the rear up and have the water flow the other way. It is consistently seeping in the forward corner on the drivers side, whether flat or tilted. Just a very small infrequent drip here and there. I wish that I could see and access under the rooftop unit, but there is just not enough room, and the hole and gasket, is recessed back pretty far from the edge of the unit. I can just slide a thin screwdriver in there. Our weather here in WI is turning into winter soon. I sure wish that I had inside shop space. I’m debating tarping the whole rig and working on it when I hit Texas in early January.
I’d love to tackle the removal myself, but the horror stories of glue, and pin holes, are deflating my enthusiasm.

Re: Roof leak from air conditioner?

Reply #12 – November 19, 2024, 06:27:21 pm

Agree it must be solved. If it continues you risk roof wood deterioration. We all wish we had inside storage.

Re: Roof leak from air conditioner?

Reply #13 – November 19, 2024, 06:45:45 pm

I'm thinkin' if you remove the plastic plenum you will have an excellent view of the roof-gasket area. Then if you just hit the roof with your garden hose, you should be able to see if the leak is at the gasket. You just need to take out those four bolts you have been tightening. Doesn't hurt anything for them to come out. The A/C won't move. Good luck.
jor

Re: Roof leak from air conditioner?

Reply #14 – November 19, 2024, 07:32:29 pm

I removed the plastic plenum. It’s too late to get the hose out tonight. First thing tomorrow, before it snows…

Re: Roof leak from air conditioner?

Reply #15 – November 19, 2024, 08:23:18 pm

Hi Mary; Your latest picture revealed a bit to me; It looks more like a leak coming in from somewhere nearby. The weight of the A/C causes the roof to sag in that location. (hence 'Lake' Newton) But with any nearby leaks, the water travels across the bottom of the ceiling towards the A/C.
I have a meter (came with a thermal temp measurer from Costco) similar to this: General Tools LCD Moisture Meter #MM8 - Leak and Humidity Detector - Pinless... It works well through the thin ceiling panels inside. It might help trace any water running through your roof, and coming out at the AC corner. I don't remember the configuration of a MB ceiling(roof). The A/C is near the coach door amidships? Ceiling penetrations for tank vents are nearby? RonB

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Re: Roof leak from air conditioner?

Reply #16 – November 19, 2024, 08:54:17 pm

I was wondering about that very same idea. The AC unit is indeed midship right inside the door. 2017 Midbath. There is nothing close by up top, except the solar panels. Everything else is 10-12” away. I really examined the interior ceiling panels, hoping to see a rusty nail, or some other evidence. I’ll invest in a moisture meter, and try that tactic. You’d think that there would be some evidence of visible wallpaper lifting, or something. I’ll head back up on the roof tomorrow to re-examine nearby penetrations. In my experience, Larry is usually right on. Thanks for your input.

Re: Roof leak from air conditioner?

Reply #17 – November 19, 2024, 10:49:35 pm

Hi Mary; I think you will be able to find your leak with that moisture detector. I used mine and it showed my ceiling at the back was wetter inside than it should be, A small hole drilled inside my back wall compartment verified it was damp. I traced it to a crack in my side roof seam. Fixed that and it has dried slowly. Easier than fixing damage. So you will be able to watch other parts of the ceiling and walls around windows, for years to come. That detector works on stick houses, and other brands of motorhomes also. It works better after a rain. RonB

Re: Roof leak from air conditioner?

Reply #18 – November 20, 2024, 01:39:07 pm

I just hand scrubbed the roof of the rig on my hands and knees. I could not find any caulking deficit, or signs of a leak. I then power washed the roof, especially under the AC unit. I now have several signs of water intrusion, complete with drips from the upper edge of the framing. A new wet spot in the opposite corner. As soon as I turned the water off it stopped dripping. My moisture meter arrives today.

Re: Roof leak from air conditioner?

Reply #19 – November 20, 2024, 07:32:13 pm

Looks like A/C needs to come off and get cleaned thoroughly and re-sealed. Surprised at LD glues the crap out of everything. Unless it is wet up above your green circle? Kind of look like it.

Re: Roof leak from air conditioner?

Reply #20 – November 23, 2024, 02:25:38 pm

Moisture meter update. The framing member that runs along the front edge of the AC is saturated. But, I also have another damp framing member in the rear of the coach. I marked the damp area with blue tape. I am unable to find any other damp spots anywhere on the ceiling. I can not find any damp area to connect the 2 areas. They are about 3’ apart. Both running side to side. Nothing to note front to back. Larry mentioned that a leak may travel 4-5’. I’m planning on having the roof AC gasket replaced. I may wait until we hit the desert SW in January to reseal and recaulk up top. Thanks for all of your input, and ideas.

Re: Roof leak from air conditioner?

Reply #21 – November 23, 2024, 02:46:22 pm

This seems unusual for a newer rig. Think I'll make a note to inspect mine during our rain next week. How is the Dometic inside cover removed?

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