2016 375 FL Rear AC leaking into Ducting - Montana Owners Club

jameswbarton · 07-27-2021, 06:09 PM

I am the original owner of this Rig and I have had the Rear AC leak problem since it was new. The AC has been removed, new gaskets, resealed but I must have missed something as it still leaks with a very heavy rain but has no leaking when I have an AC cover in place. Before I buy a new Air conditioner does anyone have the old Montana
Dometic bulletin that shows how to enlarge the AC rain drain holes etc to stop it from leaking rain through the AC Cover.

**DQDick** · 07-27-2021, 07:33 PM

If it's the same bulletin than I remember seeing it's not small drain holes that's the problem. The problem was caused by multiple holes (mounting or something) that should have been sealed when the AC was installed and weren't so that when it rains hard water can back up and flow back thru those unplugged holes. Or it might do that if it's leaning a little.

wjg315 · 07-28-2021, 05:12 AM

I had a 2016 3160RL that I had to move the rear AC over to one side about 1 1/2". It wasn't installed correctly from the factory. Took me a little bit to figure it out. With the cover off I reached down through the unit into the hole cut into the roof and could feel that the gasket on one side was barely sitting on the edge of the opening in the roof. The other side was sitting way over the opening cut into the roof. Luckily the hole was cut the correct size it was just that the AC was not mounted over the opening in the roof correctly. After I moved it over it never leaked again. Hope this helps.

jameswbarton · 07-28-2021, 06:43 AM

My unit was horribly installed as Most Montanas were in 2016. The 4 bolts were at 30 degree angles never tightened properly and the unit was not aligned properly. I had this fixed in 2016. If it was not fixed you would have had severe roof damage. There was a rash of Dometic covers not fitting properly and allowing rainwater into the unit. There was a bulletin on adding additional drain holes (which I cannot find) to allow the rainwater to drain when it came through the cover. So now I need that information or just go see if I can replace the unit maybe with a heat pump model?

Daryles · 07-28-2021, 07:08 AM

The Dometic TSB regarding the drip pan holes is in the files section

https://www.montanaowners.com/forums...hp?do=cat&id=3

jameswbarton · 07-28-2021, 09:39 AM

Thanks all! Daryles found the file for me in your file section. It includes sealing the 4 mounting bolts and drilling extra drain holes. My mounting bolts were in crooked and loose. I fixed that years ago but must have missed a drain hole. The bulletin was not published or distributed widely by Keystone and such is labelled "Heartland Units" but many 2016 Montana units had Dometic Blizzard AC units. The key to my issue is using an ADCO ac cover stopped the leak verifying it was rainwater leaking into the unit.

Jdrobone · 11-13-2022, 01:20 PM

hi,
can you help me find that bulletin?
my 2017 rear ac leaks into the return air. vents.
thank you.
Jerry
jdrobone@gmail.com

Daryles · 11-13-2022, 04:59 PM

Quote:

Originally Posted by Jdrobone

hi,
can you help me find that bulletin?
my 2017 rear ac leaks into the return air. vents.
thank you.
Jerry
jdrobone@gmail.com

Here you go.

https://www.montanaowners.com/forums/downloads.php?do=cat&id=3

Look for Dometic AC drip pan leak TSB.

Jdrobone · 11-13-2022, 05:20 PM

thank you!

You may also like: