Air conditioning in new 5th Wheel

[CLHEJ]

Hi all, just curious about air conditioners on a brand new unit.

I took delivery of a new 2021 Grand Design Reflection fifth wheel.

We are out on the maiden voyage and it seems the air conditioners are not keeping up. Is it normal to have a new unit with dual ac units for it not to keep up.

Its 93 outside, and 83 I side but the ac is set to 73.

As always, thank you in advance for the assistance!

[Lexx]

Two ac units should handle the heat just fine. Here's what we did to our trailer to help:
1) I added 20% ceramic window film to all our windows. I applied a double layer of film to the biggest window over the dinette in the kitchen. I did all of this myself using Concord ceramic automobile film from Windowfilm.com
2) On our Coleman ac units, there is a divider bar that separates the exhaust air from the return air. This divider bar was improperly positioned, allowing the cooled conditioned air to mix with the return air, greatly decreasing the efficiency of the ac unit. I moved the divider bar to the correct position and used hvac foil tape to secure it in place. Go to Mygrandrv.com and do a search on this. Many including myself, have posts with pics on how to do this correctly.
3) I pulled all the vent covers off and felt inside around the ducting. I found that some of the vents were improperly taped to the ducting system that runs around the trailer. This allowed cooled air to vent into the space between the duct and the ceiling material instead of into the room. So I used that same foil tape to make sure all the vents were sealed to the ducting with no obstructions.
4) There is now a mod that you can buy to improve the airflow out of the vents, but at the cost of blocking off the dump function of the ac unit. Folks who have installed this have reported huge improvements in their airflow. Some folks have made a version of this kit themselves out of foam board. I'm about to do the same. https://rvairflow.com/

Making these 3 changes has greatly improved the performance of our ac system. We were in Las Vegas where it was 100° plus, and we had no problem keeping the trailer in the mid-70° range.

You can also investigate adding a duct booster fan if there is any one duct that you really want more air out of.

If your trailer door/s have any kind of window, get some ReflectX insulated foil to cover the window. That was another source of heat entry into our RV.

One more thing. If you don't have a foam insert for the roof vents, get one. They really help to block out the heat from entering through the roof vents.

[TXiceman]

Leatherneck2093 wrote:


I’m surprised you could reach everything. I know I wouldn’t be able to without major surgery.

You can't reach everything, but you can seal up a lot.

Ken

[Leatherneck2093]

TXiceman wrote:

Leatherneck2093 wrote:

Ark235B wrote:
My ducts where not well connected to the unit when I purchased it. Most of the cold air went into the attic. We couldn't get it cool in the unit during the day.

I suspect your ducting is not connected, crushed or ripped and you are losing most of the cool air. There was cool air coming from the ducts...just not enough of it.

How did you get that fixed?

Got to the big box store and get a couple of rolls of the aluminum tape. Take down each vent and seal the edge. Take off the A/C ceiling assembly and tape all of the duct joins, making sure that there is no bypassing air between the inlet and the outlet. You may need to tape the edges of the fan housings. The A/C manufacturers do a horrible job of sealing the units and the installers do an equally poor job of sealing the units at installation.

Ken

I’m surprised you could reach everything. I know I wouldn’t be able to without major surgery.

[TXiceman]

Leatherneck2093 wrote:

Ark235B wrote:
My ducts where not well connected to the unit when I purchased it. Most of the cold air went into the attic. We couldn't get it cool in the unit during the day.

I suspect your ducting is not connected, crushed or ripped and you are losing most of the cool air. There was cool air coming from the ducts...just not enough of it.

How did you get that fixed?

Got to the big box store and get a couple of rolls of the aluminum tape. Take down each vent and seal the edge. Take off the A/C ceiling assembly and tape all of the duct joins, making sure that there is no bypassing air between the inlet and the outlet. You may need to tape the edges of the fan housings. The A/C manufacturers do a horrible job of sealing the units and the installers do an equally poor job of sealing the units at installation.

Ken

[Leatherneck2093]

Ark235B wrote:
My ducts where not well connected to the unit when I purchased it. Most of the cold air went into the attic. We couldn't get it cool in the unit during the day.

I suspect your ducting is not connected, crushed or ripped and you are losing most of the cool air. There was cool air coming from the ducts...just not enough of it.

How did you get that fixed?

[Ark235B]

My ducts where not well connected to the unit when I purchased it. Most of the cold air went into the attic. We couldn't get it cool in the unit during the day.

I suspect your ducting is not connected, crushed or ripped and you are losing most of the cool air. There was cool air coming from the ducts...just not enough of it.

[time2roll]

Possible you are icing up. Remove the inside covers and inspect. Look for ice on the evaporator coil. Look for the freeze sensor is placed on the evaporator coil. Plenty of posts where the sensor was poorly installed or has fallen away.

Also check the plenum divider. This separates the air in and air out. If it was poorly installed much of the air just circulates within the unit instead of being forced out to cool the RV.

I had both these issues and I am sure some of my precious cool air leaks into the ceiling cavity. You do have a lot of space to cool and the air units should be running near continuous from sun up to sun down with some cycling overnight.

[Leatherneck2093]

We have a 2019 Grand Design Reflection 28bh with a 15k AC in the living space and a 13.5k in the bedroom. We are parked in a partial shaded site with the cap oriented to the south. We are on the gulf coast and getting 90-96 degree daytime temps.

We are not having any issues keeping the rig at 70-71 degrees and the AC’s are cycling. We keep the blinds down. We have black vent covers on our bathroom and bunk room vents. When I bought the rig I checked the ducts and added foil tape to seal any leaks that I could see and made sure the returns and supplies were not short circuiting. We very rarely cook inside and the few times we have we made sure that the maxxair vent fan above the stove was open and on. We also run a dehumidifier with helps to keep the humidity between 45-50%.

I have added reflectix to the exterior walls in our cabinets and wardrobe. I don’t know how much it helps but I think every little thing contributes to keeping the rig stabilized.

FWIW if it were me I’d take it back to the dealer. Something doesn’t seem right.

[wiredgeorge]

I own an old 5th wheel (2002 Cougar 27' long) and have one 15K BTU A/C. It is pretty new and replaced the original 13.5K btu unit. Some of the things we have done are to tint the windows so 90 percent of UVs are blocked. On our camper, the ends of the A/C runs just blew into the ceiling void so these are blocked with pool noodles. I also used aluminum heat duct tape to retape and the factory tape jobs as much of the air was not confined to the ducting system but ran into the void. In south Texas, temps of 93F require winter jackets and normal July temps are generally over 100F so we also have a 8K BTU portable A/C that I vent out through a side window and our cabin temps stay pretty comfortable. Don't use the portable A/C to augment the 15K unit in the winter. As noted, your dual A/Cs should keep your cabin nice and cool so look at how much heat your windows are letting in and check to see that ducting isn't loosing your cool air. I also had to redo the seal between the return side and outlet to the ducts up in the upper unit of my A/C as that was leaking cold air. I did this by taking off the lower part and doing it from underneath.

[2012Coleman]

It may be as simple as looking at you thermostat - is it set to fan, or cool high auto?

[Second_Chance]

Pull the trim panel on the underside of the ACs and make sure the baffle that separates the cool output side from the warm return side is in place and well-sealed with foam tape or something - especially if the ACs are Dometic (the new Coleman Machs are a bit different). This is a common issue with ducted RV ACs and making sure the two streams are sealed and separate makes a huge difference.

If you have single pane windows, go to a home improvement store and buy a big roll of Reflectix "bubble foil" insulation. Cut pieces to fit inside the window frames and push the pieces into place. The bigger the window, the greater the impact (full disclosure - my wife HATED the cave feel when I did this in our Reflection 337).

Make sure the basement doors stay closed and use the main door as little as possible.

Extend the awning to protect the side of the trailer that's toward the sun if possible.

Good luck... this heat wave is brutal everywhere right now!

Rob

[memtb]

As some have stated, it will take time to cool the interior as everything inside acts as a “heat sink” .....stored heat. Until the “heat sink” is cooled, the ac will have a lot of work to do! And, as some have mentioned....on the sun exposed side, bubble foil on the windows, and the pillow in the roof vents should help. Kinda like camping in very cold....sometimes you have to assist the unit.

A few years ago, we were in Mesa, Az in August for some repairs. When at the shop (camped in their lot) we were hooked up to their power.....only an extension cord. So, we could only run one ac, it kept our 5er tolerable......barely! A second ac would have been welcome! memtb

[TXiceman]

wanderingaimlessly wrote:

CLHEJ wrote:
Thanks for your response. We have been here overnight already. It does seem like the air is coming out cool. Just not cooling the unit down during the day.

If the air exiting the unit is 10 or more degrees cooler than the air going in, thats about all you can expect.
Putting air pillows in any skylights, putting additional insulation on windows, especially those facing afternoon sun will all help.

Wrong. The air exiting the unit should be 18 to 20 degF lower than the air entering the unit. DO NOT use an infrared(laser) temp gun for air temperature. It will only measure solid surface temperatures.

With a hot RV, it may take overnight to get it completely cooled down. DO you have two 15,000 BTUH units or two 13,500 BTUH units? The A/C has to cool the air down inside the RV, and also all the cabinets, walls and furniture.

Keep awnings out if not two windy an the south and west side. Keep window shades closed, put Relectix in the windows on the sunny side, park in a shade.

Take down the inside ceiling assembly and make sure that the dusts are sealed so that it is not bypassing sit internally or blowing air into the ceiling. Use the foil tape to seal up openings.

Ken

[goducks10]

How is your 5er situated compared to the suns movement and how many and how big of windows are on the sun side?
Sitting in the direct sun all day is going to be the biggest issue IMO. Even getting a jump on it in the morning it's still going to be hard to get much lower than 10-15 degrees from the outside temps if you have lots of windows in the suns path.