Ceiling A/C ducts on left not blowing air

bharrisv65 · 01-11-2018, 12:23 AM

Hello all, I'm new to the forum and MH ownership but have had two 5th wheels previously. I've poured through many of the posts and this is a GREAT forum!

My question/problem is, my 2018 Challenger 37YT has two rows of A/C ducts in the ceiling, one row on the left and one row on the right. The right side blows out air whether the A/C vents are open or closed while the left side will not blow air either way. I'm not sure how the duct system is set up and was wondering if anyone knows why no air will come out of the left side? I have front and rear air, everything I've tried will not produce air from the left ducts. I'd like to get this fixed before hot weather gets here so if anyone can give any advice or input, I would greatly appreciate it.

Thank goodness I'm very mechanically inclined as I've had several, mostly minor, issues to deal with. I bought the coach used but it only had 1800 miles on it so it really hasn't been through a good "shake-down" yet but I'm getting it there! It's not in warranty anymore but I did (which I normally don't!) get an extended warranty since I wanted some peace of mind in the beginning in case a slide, major appliance, engine, etc. decided to take a dump. Sure, I could take it to the dealer but no telling how long it would take and I thought if it's something not too major, I could fix it myself. Besides, my experience is they don't always "fix" things or do it the right way.

Thanks for the help!

**16ACE27** · 01-11-2018, 12:36 AM

Even though you are out of warranty give Thor a call with your VIN and ask for the drawings for your coach. They will email them to you and will give you a place to start. You may also want to pick up one of these for your phone and scope out what you can see down the ducts.

https://www.amazon.com/Depstech-Semi...hone+endoscope

Laco · 01-11-2018, 01:07 AM

The ceiling AC ducts are really nothing more than channels cut in the foam insulation between the ceiling and the roof. Also the AC units discharge air into the ducts in only one direction, so there are a number of things that can cause the ducts to discharge air unevenly. I had that same issue in my former DP, and again in the Gemini.

bharrisv65 · 01-11-2018, 01:04 PM

Quote:

Originally Posted by Laco

The ceiling AC ducts are really nothing more than channels cut in the foam insulation between the ceiling and the roof. Also the AC units discharge air into the ducts in only one direction, so there are a number of things that can cause the ducts to discharge air unevenly. I had that same issue in my former DP, and again in the Gemini.

Okay, that's a start as I was thinking there might be something running the length of the MH but made out of metal, etc. If there are truly just channels cut in the insulation, that's pretty darn chintzy in my opinion but, then again, these MH builds aren't always the most technical and quality minded...

What did you do, if anything to address your issues with your previous MH's...take back to the dealer, factory, fix yourself or not fix at all? Just curious, thanks!!

blw2 · 01-11-2018, 02:13 PM

Are you sure that one side isn't set up as an air return...pulling air back to the AC?

take the inside cowling off of the roof mounted ac unit. The discharge plenum side will be more or less an open area.
Take a look to see if it's open to the roof plenum.

As Laco mentioned.... at least in mine, the ceiling is nothing more than a skin applied to a foam core with the roof sheathing and membrane above. So teh channeled in the foam are nothing more than hallows between the ceiling skin and the rest of the roof above.

The AC should be mounted with a space for the air to get into those channels. In mine, it's open to both sides.

the first photo here shows my AC. The area to the left is the intake filtered side. The other area is the output side of the fan. That black rectangle is the opening into the duct areas.

In the next photo, I was attempting to look into the duct plenum. Hard to tell, but that metal pieces is a bent metal diverted to smoothly turn the air equally front and back.

In a fairly recent thread here, somebody had found that there's only had a tiny crack and they were getting basically no airflow. Maybe there's a knock-out to open it up, I don't remember exactly how it looked. you might have to cut/drill to open it if yours is closed??? Anyway, in theirs that rectangular opening that I have was not there at all....

bharrisv65 · 01-11-2018, 11:07 PM

Quote:

Originally Posted by blw2

Are you sure that one side isn't set up as an air return...pulling air back to the AC?

Wow! Thanks for going through all the trouble to post pics and help, that's great!

In my mind, it wouldn't be very logical for them to be air returns since the return should be handled at the unit where the filter is but, we know with RV's, you can throw logic out when it comes to these builds. I couldn't feel any air blowing or suction from the ceiling outlets with the A/C vents at the units open or closed. Good suggestion though and it is plausible.

I'm going to investigate further, heeding your advice, take the A/C covers off and look at the ducts to see if it channels to both sides. I'm not going to do major surgery, I'll leave that to the warranty guys if I can't rectify it pretty easily. It would seem something is blocking that side or that side doesn't have a channel opening, which would seem more logical since neither A/C unit will feed the left side. I am assuming both A/C's feed to the ceiling outlets since there's two in the bed room. Thanks for the help!!

bharrisv65 · 01-11-2018, 11:09 PM

Quote:

Originally Posted by Tfryman

Even though you are out of warranty give Thor a call with your VIN and ask for the drawings for your coach. They will email them to you and will give you a place to start. You may also want to pick up one of these for your phone and scope out what you can see down the ducts.

https://www.amazon.com/Depstech-Semi...hone+endoscope

Great suggestion and one I didn't think of. I'd love to have the drawings on my coach as it would be invaluable when working on things or to diagnose problems...not that we ever have any!

Laco · 01-11-2018, 11:23 PM

The air returns, at least on mine, are part of the grillwork on the ceiling, right under the AC unit. The cooled air flow out, discharges in the ceiling, and makes its way, the best it can, to the vent outlets distributed throughout the coach. My former DP, a fairly high end coach, was the same way, and though air flow out the registers varied a great deal from register to register, the total airflow out was ok. The same seems to be true on the Gemini too. As far as the Gemini, since I have added a second AC, my cooling capacity is the same as it was in my former 41 foot coach, with only about a third of the cubic feet. Needless to say the capacity is high enough that cooling is pretty effective.

bharrisv65 · 01-24-2018, 12:13 PM

Well, it ended up being a simple fix but another one of those frustrating quality issues we have to deal with. There's a divider separating the intake side of the A/C unit from the cooling side which was crooked in both units, neither one was secured in any way except by sheer friction and by the bottom of the grillwork holding them in place. I have attached a pic in case anyone runs into this problem again, I took a pic of the correct position of the divider but it wouldn't load. The pic in BLW's post above shows the correct position. Notice how the divider is open to both intake and cooling side. This, in effect, was causing the intake side to draw from the cooling side, decreasing both the cooling and discharge of cool air from the units. After securing the dividers where they should be, I have great flow out of ALL ducts. Thanks to everyone who offered help and especially to you BLW for the pics as my units looked exactly like yours and I was able to determine exactly how the dividers lined up.

Now on to the next repair journey as it (they) arise! Be safe!

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