Very unhappy with new AC system!

[Good Life]

Originally Posted by TheKothes

Installed the PVC and cleaned out the sawdust. Tied up the wires as well. It is noticeably louder which tells me there is more air flow. We will find out on the next venture.

Did you cut the flanges off the registers that is sticking up in the duct? Mine were almost touching the top of the duct work?
I also added 3 more registers which will quieten down the rumbling you hear which is from pressure build up!
Also be sure to seal up the joints in the upper portion of foam shroud, if you didn't, turn on unit and go up there, you will be amazed of the cold air escaping!

[vipermanden]

Seal up the joints in the upper portion of the foam shroud?? Where is this located? Also, how do you know where to add registers, and what tool did you use to cut the holes?

[TheKothes]

I have not trimmed the registers yet. Done sweating for today. I did find out on this unit all of the registers are on a common zone. I found that design a bit odd. I did look at them and mine stick up about a half inch. I did tape up the foam shroud before I put the covers back on. What did you use to trim the flanges?

[TheKothes]

On the roof when you take the cover off the AC there is a Styrofoam cover or shroud that is over the return air portion of the unit. You will want to check it for leaking air and tape/seal it up where you can to improve your efficiency. I suspect the ducts line up and there is a "raceway" duct from front to back. I am assuming that is what Good Life did when he added his registers.

[Good Life]

Originally Posted by vipermanden

Seal up the joints in the upper portion of the foam shroud?? Where is this located? Also, how do you know where to add registers, and what tool did you use to cut the holes?

Up on top of your unit, remove the plastic cover,then the top half of the foam shroud which is the only way I could get to the coil to clean and get the bundle of wires out of the return plenum, I went in between the two rear vents and the next two over my Island-installed 1 in each side, then one towards the front of kitchen just behind the command center closet!
I used this: http://www.homedepot.com/p/Klein-Too...3731/203828012

[Good Life]

Originally Posted by TheKothes

I have not trimmed the registers yet. Done sweating for today. I did find out on this unit all of the registers are on a common zone. I found that design a bit odd. I did look at them and mine stick up about a half inch. I did tape up the foam shroud before I put the covers back on. What did you use to trim the flanges?

1/2 " from flush will not hurt you, mine were almost touching the top of duct, I used a pair of straight cutting tin snips!
Also my unit has 2 common ducts running from front to rear, both a/c units dump into them!
I also removed the (4) return grills, took a marker and marked the inside max that it could be cut out and did so using a left/right tin snips, re taped the edge!
Before you reinstall the return grill base reach inside the duct towards the outside edges or trailer and vacuum the saw dust left by factory!!

[lilpeach]

Originally Posted by bshgto

I`m not saying I don`t like my camper I do, front cap and a landing gear motor is the only issues I have had in 3 years with this unit, added 3 vents to the a/c and a dehumidifier to the unit and it`s better. I`m just saying a 3791RD is going to come with what issues? I have none now do I want to role the dice? I`ll just wait till Hershey in a few weeks and see what`s up.

I was at the Hershey RV show Sept 13th. Took us 3 days from 10 am to 8 pm to see campers, excluding motorcoaches. A lot of nice units. Montana has a considerably lighter interior. Like the new oblong look of fireplace. The light switch in bathroom is at the door so you don't have to fumble your way in to find it. I forgot to look to see if the couch platform is wider so that couch legs aren't hanging in mid air. This I did notice in SOB no issue with couch. The floors have the wider plank look and lighter in color. Cabinets sorta gray brown. In the 3000RE, which is now the 3130RE they put the frig on the other side of stove so now frig is accessible without opening slide. Would've traded in my mine except I just traded in my 2016 for a 2017 in January. Couldn't afford the hit. Plus Dad said, "Don't trade!" Overall nice show!! How did it go for you in your search?

[vipermanden]

Good Life, how did you get a 12" piece of 1-1/2" sch 40 pvc pipe to go into the return vents? I just put in one 4" piece. I plan on doing more now that I see what you have done, but how did you get it in there?

[Good Life]

Originally Posted by vipermanden

Good Life, how did you get a 12" piece of 1-1/2" sch 40 pvc pipe to go into the return vents? I just put in one 4" piece. I plan on doing more now that I see what you have done, but how did you get it in there?

I didn't use 1 1/2" sch 40, I used these http://www.homedepot.com/p/Everbilt-...9786/205153652
They also come in 12", you can roll them in thru your return air duct out by the outside walls by removing the grill and base!
I used a very small amount of glue to hold them together just so they didn't come apart and get lodged!
All you are trying to do is open the collapsed 2X12" duct kinda like a egg shape!

[Former StClairSailor]

You have to be very careful with installing the PVC into the air ducts. If you run into a tight spot and push, you can easily tear into the duct and now the air runs into the area above the ceiling. I found my duct work in the A/C return had collapsed. I saw a flex hose which was wire wrapped heavy soft plastic. It won't collapse and will not damage the duct. You have to pull off the A/C return cover and go up top and remove the Air Conditioner, then run a wire from the return vent to the A/C area to guide it and push it through. Then screw or glue it down in the A/C area to hold position. While you have the A/C out take a look at the venting. I saw very poor taping in that area. I also saw quite a bit of sawdust. Did this on both A/Cs. The air movement was very much improved. I used a IR thermal gun to check the temp of the A/C return, 76 degrees. Then checked the output, 55 degrees. Similar reading were found from the front A/C. The outside temp was 91 degrees. The temp rose in the unit to 80 degrees. I then checked the walls. On the side the sun was not hitting, the wall was 81 degrees. On the sunny side wall the temp read in the 90s. Inside the rear cabinet above the window the temp was 101 degrees. So if the A/C is functioning properly now, what's the problem. Draw your own conclusions, but I believe I figured out the cause.

[DQDick]

I believe you're right. Besides the fixes on the AC we also added 3/4 foam to the outside edge of all our cabinets and the laundry area and it also made a difference.

[Woodcraver]

See thread "air conditioner" by chasers. Lots of owners having problems with Ac system. I'm one of them.

[jeff_banning]

Supposedly Keystone is acknowledging that when they installed the roof insulation and then installed the roof it crushed the foam duct-work on some units. I believe this is now a know issue and dealers will start the modifications mentioned even though many of us have already done it with varying results.

[Golfmedik]

Originally Posted by jeff_banning

Supposedly Keystone is acknowledging that when they installed the roof insulation and then installed the roof it crushed the foam duct-work on some units. I believe this is now a know issue and dealers will start the modifications mentioned even though many of us have already done it with varying results.

When mine was at the factory for this and frame issues back in April, Keystone kept trying to blame Dometic, even though several of us had already seen the crushed ducts, high rimmed vents, sloppy made returns and too few of vents. How many hundreds of people telling you that you have a problem does it take for you realize or admit it? Since our unit has came back, it has been working better if we are on 50A. With 30A, no difference. So now we use the 2-30s to run both of the units and it has worked out well. Even FR came out with a solution that I posted way back, so it is about time they recognize and try to solve the problem.

[Ironbrow]

In our previous 5th wheel (a KZ) we installed a Micro-Air soft start card so that we could run our 15K AC on a Honda 2000 generator. It worked like a charm and we could run everything else at the same time.

We just purchased a new 2018 3790RD Montana 5th wheel and the first thing I did was order 2 of the soft start cards. I can run both AC's on any 30 amp connection, or I can run two Honda 2000's in tandem while dry camping (boondocking). Sometimes I only need to run one Honda and one AC. I keep hoping that all RV AC manufacturers will start including the soft start feature in their units. But for now we're just happy we can install our own.

[Seasonalcamper]

I too had this same issue this past weekend with my 2017 montana 3950... Could not get unit to cool down...Air temp was 98 and humidity was at 92%. also could only use rear unit as i'm on a 30amp post. I never tried using both as i was told you could not use both ac's. I will be trying that fix with pvc cause when i did check returns they were very close to vents didnt seem like much room for air to enter. You would think the newer the trailer one would have the better the A/C ...but I too very disappointed...just happy we dont have this heat all the time...

[Seasonalcamper]

Originally Posted by kozzy

I have not witnessed the issues that are all listed here, thanks god. Im sure my units can perform better. One thing I can add, that made a difference I can feel was simply removing all the air return covers and cleaning the ducts with a shop vac. I could not believe the amount of saw dust and wood shavings from the install left in there. I also removed the covers on the units themselves and vacuumed them out. Now I have not done any actual temperature readings, but I instantly felt a difference in the cool air coming out into the coach. I am curious if there might be some type of recall to fix the air flow issues?>

what did you use to get into vent to vacumn out

[richfaa]

We have not experienced any A/C issues with both our 06 3400 and our 13 3402 both with 2 A/C's. W have full hookups 50Amps here on our property and have been working on the interior that last few days with both A/C running.It has been in the mid to high 90's with very high humidity (Northern ,Ohio) Yesterday the temps were in the mid 90's with high humidity. We measured the temps at the A/C vents.They were 51.3 degrees with good air flow. That has been about the normal reading. The inside temp is set at 78 degrees and it was maintained. Outside temp is a bit lower to day and while in there the A/C cycles on and off while maintaining the 78 Degree temp.

This 3402 is a pretty Big Sky colored black and a couple shades of gray and a bit of white. When in Shawnee,OK two summers ago it was 107 at the fairgrounds and no shade. The temps on the outside gel coat reached 117 to 124 degrees during the dayand the inside walls were 90 degrees in many places. The A/C system ran continuously and was hard pressed to keep the inside temp in the mid 80"s.It did wring the humidity out. Next to us was a friend in a brand new Jayco and it was no better. Many folks had fled to the inside buildings for relief. We have been in many parts of the country were two A/C operating normal are just not enough for a large RV.

[DQDick]

Originally Posted by Seasonalcamper

I too had this same issue this past weekend with my 2017 montana 3950... Could not get unit to cool down...Air temp was 98 and humidity was at 92%. also could only use rear unit as i'm on a 30amp post. I never tried using both as i was told you could not use both ac's. I will be trying that fix with pvc cause when i did check returns they were very close to vents didnt seem like much room for air to enter. You would think the newer the trailer one would have the better the A/C ...but I too very disappointed...just happy we dont have this heat all the time...

In a way, we only have ourselves to blame for the Whisper Quiet issues. Years of bitching about the noise of the old AC units that actually worked got Keystone to respond with this solution.

[fre1fred2]

we have a 2016 3950BR, last year we went camping when it was in upper 90's and inside would only get down to around 82-84. Went home that weekend and did the return mods and ceiling vent mods. This weekend was first weekend we have camped since I did the mods where the temps got into the upper 90's. Guess what....camper stayed around 73 and was not in any shade so in my case...the mods definitely helped.