AC Condensation Dripping From Ceiling

[GUS2000]

2024 DS4369 - Wanted to share an experience with everyone here so that in case you have a similar issue, this will hopefully help you resolve it.. Since last year we had been having an issue where we would get condensation dripping from the ceiling. All drain pans were draining well, insides of the ducts were dry... only moisture seen was between the ceiling and the supply duct. Running a borescope camera could detect no gaps in the duct itself.. Had two mobile techs pull the AC off and say that it looked good, but to this point i had not seen it first hand.. However, this week we are in Texas and it started once again (see photo of water droplets formed on duct and water pooling below that).. This time i decided i go on the roof myself this time and removed the rear AC with the help of a local mobile tech. He also said that the opening looked good, but I questioned the gap in the foil tape.. when i touched that area, the duct material was soaking wet... Foil tape was applied and all areas sealed, and the AC reinstalled using a Steele Rubber gasket. 48 hours later we are dry (see photo taken 24 hours post correction) with no condensation forming in the attic. Photo is the gap in the foil tape just in case anyone sees something similar so you can see how a small void in tape will cause a condensation issue in the attic airspace..

[ThunderRidge]

Get up on your roof and check the 4 hold down bolts for each air conditioner. I experienced a problem similar to this when my coach was new. All four hold down bolts for all three air conditioners were extremely loose. Came from the factory like this. Once I tightened all the bolts I have never again had this problem, going on seven years now.

[JPSiouxa]

Originally Posted by GUS2000

2024 DS4369 - Wanted to share an experience with everyone here so that in case you have a similar issue, this will hopefully help you resolve it.. Since last year we had been having an issue where we would get condensation dripping from the ceiling. All drain pans were draining well, insides of the ducts were dry... only moisture seen was between the ceiling and the supply duct. Running a borescope camera could detect no gaps in the duct itself.. Had two mobile techs pull the AC off and say that it looked good, but to this point i had not seen it first hand.. However, this week we are in Texas and it started once again (see photo of water droplets formed on duct and water pooling below that).. This time i decided i go on the roof myself this time and removed the rear AC with the help of a local mobile tech. He also said that the opening looked good, but I questioned the gap in the foil tape.. when i touched that area, the duct material was soaking wet... Foil tape was applied and all areas sealed, and the AC reinstalled using a Steele Rubber gasket. 48 hours later we are dry (see photo taken 24 hours post correction) with no condensation forming in the attic. Photo is the gap in the foil tape just in case anyone sees something similar so you can see how a small void in tape will cause a condensation issue in the attic airspace..

Air conditioning condensate is pure distilled water, a very aggressive penetrant for any hygrophilic material -- and nothing in your RV is more hygrophilic than plywood! Take some wet plywood, add a few splatters of bird poop, and your roof will be rotting out within MONTHS.

[GUS2000]

Originally Posted by ThunderRidge

Get up on your roof and check the 4 hold down bolts for each air conditioner. I experienced a problem similar to this when my coach was new. All four hold down bolts for all three air conditioners were extremely loose. Came from the factory like this. Once I tightened all the bolts I have never again had this problem, going on seven years now.

The point of my post was to show the root cause of my specific issue.. (gap in foil tape). Torque had already been checked as it was looked at by Newmar and two mobile techs and they missed seeing that gap in the foil tape. The bolts were all per spec and when i reinstalled it with the new seal, i ensured it was torqued correctly...

[redbaron73]

Originally Posted by GUS2000

The point of my post was to show the root cause of my specific issue.. (gap in foil tape). Torque had already been checked as it was looked at by Newmar and two mobile techs and they missed seeing that gap in the foil tape. The bolts were all per spec and when i reinstalled it with the new seal, i ensured it was torqued correctly...

What is the proper torque? I have this issue in my rear air and will want to check for the gaps you mentioned.

Also, can you provide a link to the gasket you used?

[GUS2000]

Originally Posted by redbaron73

What is the proper torque? I have this issue in my rear air and will want to check for the gaps you mentioned.

Also, can you provide a link to the gasket you used?

40 – 50 inch‑pounds is the torque per Dometic..

here is a link to the gasket!! (side note - Newmar suggests that these gaskets are replaced every two years)

https://www.steelerubber.com/camper-rv/ac-gaskets

you will need the standard gasket and the plenum divider gasket..

[shepardmike]

Good find. Thanks for posting John

[Dutch Star Don]

Good find......kind of makes you wonder why the mobile techs missed it. When water is dripping, you always want to feel around. Glad you got it resolved as it can be an annoying issue.

redbaron.....I looked up some old posts and found the same as noted above 40-50 inch pounds When I had the direct through the roof units on my Diplomat (no ducting) I liked to use a 1/4" drive socket set to tighten, so I wouldn't over tighten and squeeze the seal too tight.

[GUS2000]

Originally Posted by Dutch Star Don

Good find......kind of makes you wonder why the mobile techs missed it. When water is dripping, you always want to feel around. Glad you got it resolved as it can be an annoying issue.

redbaron.....I looked up some old posts and found the same as noted above 40-50 inch pounds When I had the direct through the roof units on my Diplomat (no ducting) I liked to use a 1/4" drive socket set to tighten, so I wouldn't over tighten and squeeze the seal too tight.

thanks!

The first mobile tech didn't even remove the ac. He said the divider gasket is fine so it cant be coming from the roof area.. Newmar service removed it and didn't see anything and told me we were just in a high humidity area and that it was normal... yeah no.. then this last week, the tech that came talked to Newmar's support tech line that is dedicated to mobile techs, saw the humidity in the ceiling and told me there was nothing he could do.. He didnt want to remove the unit.. After me suggesting it multiple times, he finally agreed too and i was on the roof with him.. When i saw the gap in tape I was really surprised Newmar's tech didnt see it at the mothership.. i used a few feet of tape to really seal all around and ensured no gaps or bubbles in the tape...

i sent all these photos as well as video to Newmar in hopes it will help them better find issues like this and hopefully prevent them from happening from the factory.. since i posted this, i have heard from at least five people who said they had similar issues that no one could find the source.. .it will be interesting to see if they have the same root cause..

[redbaron73]

Originally Posted by Dutch Star Don

Good find......kind of makes you wonder why the mobile techs missed it. When water is dripping, you always want to feel around. Glad you got it resolved as it can be an annoying issue.

redbaron.....I looked up some old posts and found the same as noted above 40-50 inch pounds When I had the direct through the roof units on my Diplomat (no ducting) I liked to use a 1/4" drive socket set to tighten, so I wouldn't over tighten and squeeze the seal too tight.

I once made a mistake about paying attention to In/lbs vs Ft/lbs...this was on a jetski. Adding a step and was amazed that it wanted the torque to be 75ft lbs into the thin fiberglass with no back bolt. I was skeptical after the first turn and stopped to call the local dealer...this was when I was educated on inch lbs of torque...and had to buy new tools.

I now pay real close attention -- was almost a disaster.

[UpDown]

GUS2000
First, thank you for the details on how solved the condensate issue. I’m a bit curious about the Newmar recommendation to replace the gasket every two years - was this from a verbal conversation with Newmar rep or did you find it in the Newmar’s owner’s bag of instructions. We’ve used Class A’s for 25 years (on our fourth rig) and never had a gasket issue (lived and traveled much in both desert and high humidity areas)

[JRI]

Originally Posted by GUS2000

The point of my post was to show the root cause of my specific issue.. (gap in foil tape). Torque had already been checked as it was looked at by Newmar and two mobile techs and they missed seeing that gap in the foil tape. The bolts were all per spec and when i reinstalled it with the new seal, i ensured it was torqued correctly...

Your post was very clear and isn't the problem. The problem was the responder not reading your post before responding.

[Sam 3]

Thanks for posting the problem and the resolution. Years ago our non ducted AC poured water on the inside of our AC. We shut it off as we were camping. I had a small portable fan to use. We got on the internet and fund the fix for our problem. The bolts on the inside loosened up with travel. Dad to the rescue with his socket set. He tightened the inside bolts and it snugged up the seal. Don't over tighten. Never had this problem for many years. The AC bolts can loosen up with the vibration from travel.

[lostinfla]

When pulling the AC units and reinstalling, I always fill the hole with silicone before putting the bolt back in. Makes a good seal to keep water out of the holes and rotting the wood and keeps the lag bolts from loosening up.