collapsed a/c return ducts

[2 Yoopers]

After reading a lot of the posts here I checked the return air ducts on my 2015 3711fl. I found them collapsed and the openings cut way smaller than the vent. I used a Dremel with a carbide endmill and trimmed the openings bigger, then taped with aluminum tape. Added the pvc in the center to open the ducts back up. I found new outlets at Dwinc on the web, model is 8850 and they are larger than the original outlets, adjustable, closeable and flow 20sq. inches of air, compared to the stock 12sq. inch ones. Used dremel tool to open hole to 5 7/8” then taped the gaps up between duct and ceiling. New outlets are 7/8 tall instead of sticking way up in the ducting. Replaced 4 in the front living area, 2 in the bedroom, 1 in the bathroom and added 2 in the kitchen where there were none. This worked great, very pleased with the cooling now.

[Garybricker]

Has anyone made a iTunes of this or will there be a forum on this at the rally

[DQDick]

For a large number of reasons I doubt it, but there will be a number of us at the Rally that have done these mods and more. Our rig has these plus: added insulation, heat cutting window screens and a third AC that can run right along with the other two. That's the great thing about the National Rally. We learn alot from the Keystone arranged demonstrations and also from each other.

[BUBBA-NONNIE]

Originally Posted by ingalmi

A/C cycling, return ducts need to be free of restriction so check this first.
Next;
Pretty normal if operating in auto fan. Bedroom unit if it’s the front one will cycle more because of cooling room area. I use high fan on both until just before ready for bed then switch to low fan. Just personal preference. Here’s what some don’t know about, remove the thermostats off the wall (2 screws) and you’ll find a huge hole where they pass a small wire through. Guess what the thermostat is really reacting to? The inside of an uninsulated wall! Use tape or insulation to cover/plug the hole allowing enough room for the wire. Will make a difference in how the system works. Good luck and happy camping

Thank you for the information on the thermostat. I have a 2017 Montana 3000RE. My AC was cycling off and on, so I thought. After talking to Dometic, I was told the unit is working like it is supposed to work. Dometic told me to place the fan on high or low and it would stop the cycling, which it did. I thought the AC was cycling but it was the fan.The other thing I learned was to prevent the fan from cycling on Auto I had to close the bedroom door and within minutes after doing that it stopped cycling.

[Phil P]

Originally Posted by DQDick

Consider yourself lucky. Yes they have changed. After enduring complaints about the noise the older units like yours makes they came up with the Whisper Quite system. The return air on those units is near the sides of the ceiling and then it is ducted back to the unit. Dometic came up with the unit, but the real problem comes in how the manufacturers are installing them and Keystone isn't alone in that.

Thanks


I thought there was something even more wrong with me than normal LOL

[Baldicon]

Originally Posted by DQDick

My 2017, built in February, doesn't have the plastic on the end of the return air that they added in the fall of 2017 and on. Would be interested to know if these actually solved the problem.

My unit was manufactured Spring 2018 and it does have a hard plastic 90 ell connecting the ductwork to the return register if that is what you are talking about. It also has what looks like a spacer in the middle of the return ductwork which I assume is supposed to prevent collapse (see my earlier post with picture). I was hoping someone with a pre-Fall2017 unit could tell me whether their unit has this spacer. I'm trying to determine what they actually changed. Been in our unit about 6 weeks now and so far, no problem with cooling and you can feel the air flow. Again, just trying to determine whether I need to go ahead and add the PVC pipe sections.

[LaydBack]

My 3731FL was made in late March. I notice on my front unit, each return has 1 side blocked off with the metal tape. I want to say that on the ODS, it’s the forward facing side, and on the DS it’s the rear facing side of the returns that are blocked off on the front unit. I’ll have to check the rear unit, but is this the case for anyone else? Seems I read where someone mentioned each of their returns working both directions, and installing 8 pieces of pipe in the 4 returns, 1 facing each way. Maybe I misinterpreted?

[DQDick]

Originally Posted by Baldicon

My unit was manufactured Spring 2018 and it does have a hard plastic 90 ell connecting the ductwork to the return register if that is what you are talking about. It also has what looks like a spacer in the middle of the return ductwork which I assume is supposed to prevent collapse (see my earlier post with picture). I was hoping someone with a pre-Fall2017 unit could tell me whether their unit has this spacer. I'm trying to determine what they actually changed. Been in our unit about 6 weeks now and so far, no problem with cooling and you can feel the air flow. Again, just trying to determine whether I need to go ahead and add the PVC pipe sections.

Sorry, missed you were looking for that. Mine does not have anything in the middle of the duct.

[Baldicon]

Originally Posted by DQDick

Sorry, missed you were looking for that. Mine does not have anything in the middle of the duct.

Thanks DQDick. I was told they were going to make some modification Fall 2017, and that's one of the reasons I waited until Spring to order. I was trying to figure out exactly what they changed. So it looks like the plastic 90 ell and added the internal spacer. So far, so good. But I will be taking a look inside periodically for any signs of collapse. Thanks again.

[mbjam359]

Our 2811MS was manufactured in June or July 2017. Our returns are not collapsed and I believe we have spacers in all 4. I did remove every other louver on the outlets. We have been pretty pleased to this point. We do utilize a portable fan or two just because we like moving air. I am sure this helps but not a necessity.

[mtlakejim]

Originally Posted by 2 Yoopers

After reading a lot of the posts here I checked the return air ducts on my 2015 3711fl. I found them collapsed and the openings cut way smaller than the vent. I used a Dremel with a carbide endmill and trimmed the openings bigger, then taped with aluminum tape. Added the pvc in the center to open the ducts back up. I found new outlets at Dwinc on the web, model is 8850 and they are larger than the original outlets, adjustable, closeable and flow 20sq. inches of air, compared to the stock 12sq. inch ones. Used dremel tool to open hole to 5 7/8” then taped the gaps up between duct and ceiling. New outlets are 7/8 tall instead of sticking way up in the ducting. Replaced 4 in the front living area, 2 in the bedroom, 1 in the bathroom and added 2 in the kitchen where there were none. This worked great, very pleased with the cooling now.

I could not find a dwinc brand of vent on the web. Can you verify the brand please.

[2 Yoopers]

Yes, it is Dwincorp.com. They handle quite a few of the outlets and other rv parts. I paid 6.00 for each outlet, includes the collar that screws into the ceiling and the snap in adjustable louver that covers the screws. Shipping was fast as well.

[mtlakejim]

Originally Posted by 2 Yoopers

Yes, it is Dwincorp.com. They handle quite a few of the outlets and other rv parts. I paid 6.00 for each outlet, includes the collar that screws into the ceiling and the snap in adjustable louver that covers the screws. Shipping was fast as well.

Ok I was goggling just dwinc

[jeffba]

https://www.dwincorp.com/product-cat...ucts/ac-vents/

[mtlakejim]

Originally Posted by jeffba

https://www.dwincorp.com/product-cat...ucts/ac-vents/

I found it thanks for the followup

[cghsatx]

I have a 2019 3731 and am wondering if the return air is partially blocked , as I have cooling issues. Appears that only one side of the duct is open, and maybe 1/2 inch of opening. I dont feel much if any air flow but there must be some as the the vents have air flow. The LR area filters are almost clean and but the bedroom has had to cleaned

[BUBBA-NONNIE]

I have a 2017 Montana 3000RE. I had the same problem. I propped it open with 1 1/4” capped pvc. Cut just slightly shorter than the width of the duct.

[cghsatx]

Originally Posted by Texan

I installed 1- 10''- 1/14'' diameter pvc in each duct. I removed the register and stuck pipe inside length wise of the register then turned the pipe toward the center of the room and pushed the pipe in flush with register or beyond keeping the pipe in center of the duct. Some use 2 pipes in each register with one on each side but one seems to suffice as long as you install pipe in center of duct as the center seems to be what sags.Like golfmedic said take the rough edges off of pipe that has been cut. Also scoop out with your hand the sawdust just inside the register then vacuum out the rest.

Anyone know how these ducts are put together? I did the PVC treatment on my 2019 3731(it had all the commonly reported AC issues) last weekend but was a little concerned if the PVC would put too much pressure on the duct. If its just taped together pieces of Styrofoam, it might split. It was easy to slide in the PVC and it did open up the space quite a bit, but I have no idea how long the return air duct is and maybe does it collapse down again past the end of the PVC?

[Mikendebbie]

There are several "Keystone Montana Factory Tour" videos on youtube.
At times in each video you can see the ducts.
I like the "Home with the Hoopers" video here...ducts can be seen at ~10:00 mark.

https://www.youtube.com/watch?v=o0W2PeLlUBY

I took some screen shots from a couple of videos that you can look at below.
The first screen shot is from "Home with the Hoopers" video and it does indeed look like a styrofoam box. I have never touched the interior of mine...seems like if it was styrofoam you could see it! In the second pic you can see a joint taped together with aluminum HVAC tape. Pay attention to the dates of the youtube videos because duct material may have changed over the years.

[John Sigmone]

My 2 ducts are definitely collapsed. Can someone please tell me the length from the return to the end of the duct? And is it a straight line to the AC UNIT?