A/C ????

[2 Yoopers]

I did the pvc in the return vents, that helped the flow a lot. I also purchased the Jet Stream air out vents from dwincorp.com. They offer them in a same size direct replacement style with a shorter inner sleeve that does not protrude into the narrow duct to far.
They also offer a larger version which is what I used. I removed the old restrictive vent and sleeve. Traced a line showing the bigger hole needed on the ceiling.I used a dremal with a straight 1/8 carbide cutter to easily cut through the ceiling and the duct.
I then used the aluminum duct tape around the hole and duct. I installed the new sleeves and snapped the vent on and air flow greatly improved.

[Ram Montana High Country]

thanks for the link - interesting vendor

[mtlakejim]

We live in the ideal test bed for A/C units (open desert just north of Carlsbad, NM. IE: no shade consistent temps above 100F for months).


Taking our cues from this forum and good neighbors in the same park, we used 1 1/4" PVC pipe cut slightly shorter than the return vents on our front A/C unit to open up those vents. We then cut every other fin off the existing discharge vent covers. This alone allows our 42' 381TH to stay about 20F below outside temp.


Out of an abundance of precaution and to ensure the safety of our two Chihuahuas while we are at work, we bought a large portable A/C from Wal Mart ($350). It sits in the kitchen area and we set it to higher temp as a backup just in case. The exhaust hose is directed to a smaller window on the slide and I routed an extension cord from the power pedestal directly to the unit. That way if the 50amp and or coach power goes down we still have the back up to save the pups if there is power to the pedestal 110plug. In addition we bought a TempStick temperature alarm that both emails and texts us both if temps get too high.


We do plan to replace the portable third unit with a third roof A/C installed into the power vent in the kitchen at some point. But like the portable, I plan to wire that unit completely separate from the rest of the coach. Doing so also will allow us to use two A/Cs with no issue at a campsite that is 30amp main power in the future.


In summary, you can keep these trailers cool if you have ample air circulation. Anything you do to improve airflow is going to help!

[BandBmalin]

One suggestion I haven't seen mentioned that helped me out a lot in my last travel trailer was putting a piece of a pool noodle just past the last vent on each end of the trailer. I've not yet looked inside these runs yet, but in my TT, the main air channel in the ceiling ran from one end to the other with vents along the way to let the air out. By using a piece of pool noodle right after the end vents on each end of my trailer, I got MUCH more air flow since the air wasn't going down past my vent and doubling back. I later swapped out my vents with high flow versions like others have suggested. (Did the pool noodle trick in my son-in-laws TT with great success also!)

[ebds2019]

Originally Posted by Texan

Most likely your return air vents in the den on the ceiling are partially collapsed and so not working properly. I cut me 1 1/4'' diameter pvc pipe 9'' long and installed them in the return air ducts to open them up. I used 2 in each vent where some have used 1. I stuck my pipe in the vent parallel with the vent then turned the pipe and inserted it in the duct toward the center of the rv. You can push it the whole length of the pipe or more up in the duct and this will help the return air work much better. I am sure there are some other ideas others may have but this is something many on this forum have done that is very easy to do for less than 10 bucks.

OK folks I have read about this mod several times and finally decided to look into it more seriously. But still having some understanding issues. I have a 3810MS with an arched roof. A little while ago I took the cover and filter off one of the returns in the living room. I measured the distance from the top of the return to the bottom of the return right at the air register. It measured about 1". I don't have a ladder with me so I can't get up high enough to actually look into the register (going to try to use my phone camera with flash later).

I am confused. If the vent measured 1" at the opening and the pvc you are all recommending is 1-1/4" how does that make much of a difference? What am I missing here? Where is this closed up vent supposed to be?

Also, in my 3810MS there are two A/C units, one in the living room and one in the bedroom. If I turn on the living room unit there is also some cool air coming out of the bedroom vents. How can that be? Aren't they two separate cooling subsystems?

[Mikendebbie]

I have a 2018 model. Below is a screenshot from the sales brochure. These ducts look semi-rigid like duckboard. This shows the supply side. I have no idea if return ducts are similar. Are these the ducts that have the collapse issue?

[Ram Montana High Country]

Originally Posted by ebds2019

OK folks I have read about this mod several times and finally decided to look into it more seriously. But still having some understanding issues. I have a 3810MS with an arched roof. A little while ago I took the cover and filter off one of the returns in the living room. I measured the distance from the top of the return to the bottom of the return right at the air register. It measured about 1". I don't have a ladder with me so I can't get up high enough to actually look into the register (going to try to use my phone camera with flash later).

I am confused. If the vent measured 1" at the opening and the pvc you are all recommending is 1-1/4" how does that make much of a difference? What am I missing here? Where is this closed up vent supposed to be?

Also, in my 3810MS there are two A/C units, one in the living room and one in the bedroom. If I turn on the living room unit there is also some cool air coming out of the bedroom vents. How can that be? Aren't they two separate cooling subsystems?

IMHO - get a work platform of ladder to easily work from. once up there: see if you can easily push the top of the duct up to increase the space by 1/4". If it opens up, that gives you 25% more space. The return side is more of an issue. On the pressure side, limiting obstructions is important to not hinder flow. kinda like a rock in a stream


If you are a gadget person, get a bore scope to run off your phone. This allows you to see all sorts of places normally not accessible .

[MidMOTraveler]

ebds2019 There are 2 duct runs in the ceiling left / right the AC unit sit on top of these the return airs are independent. So you get air all over when either AC is running.
I did the the pvc fix along with some trim work and sealing with tape
Made a huge difference, removing a couple of the vent covers also is a tremendous help.

[waynemoore]

The return side of the AC is the suction side. The AC is sucking in air to cool and send out the discharge side. Ie cold air coming from the vents.

The suction side is the problem as the AC is sucking the air in it also sucking the air duct in together so to speak. The PVC pipe holds the duct open not allowing air restriction.

Or better said the return ducts are not structural and will collapse causing air flow restrictions. Starving the AC air to cool and return to the RV.

[mtlakejim]

Originally Posted by ebds2019

OK folks I have read about this mod several times and finally decided to look into it more seriously. But still having some understanding issues. I have a 3810MS with an arched roof. A little while ago I took the cover and filter off one of the returns in the living room. I measured the distance from the top of the return to the bottom of the return right at the air register. It measured about 1". I don't have a ladder with me so I can't get up high enough to actually look into the register (going to try to use my phone camera with flash later).

I am confused. If the vent measured 1" at the opening and the pvc you are all recommending is 1-1/4" how does that make much of a difference? What am I missing here? Where is this closed up vent supposed to be?

Also, in my 3810MS there are two A/C units, one in the living room and one in the bedroom. If I turn on the living room unit there is also some cool air coming out of the bedroom vents. How can that be? Aren't they two separate cooling subsystems?

The "quiet air" return air ducts will only be on one unit (usually the living room unit). The ducts will collapse in the middle about half way to the center of the unit where the actual AC unit is located. It will be particularly noticeable when the unit is running and pulling a bit of vacuum on the ducts. So the short answer is you will have to get on a step stool and look down the vent to see what everyone is talking about. No real surprise as the ducts are not much heavier than a cereal box with the weight of a roof on top of them!!!

The discharge ducts are tied together with the AC units on either end of the unit. So yes, you will get some air out of all the vents even with only one unit running. There should be an option on the AC unit that does not have remote "quiet air" return ducts to dump the discharge air directly out of the unit without it going to the vents. That feature is handy to cool off the bedroom quickly. We leave the dump cracked open just a tad to make it cooler while sleeping.

Trust the folks on here and just do all the mods. They will work.