Are 2 roof A/C units ever enough?

[bamaboy473]

We are usually in the Southeast so air conditioning is important to us. Our American Eagle was 40' and the two 13,500 units barely kept up when things got into the 90s.

We are looking for another coach now and I wonder whether we should have 3 A/C units. I'd rather not go to 42' but can't find any 3-unit coaches at 40'.

If we upgrade to 15,000 units, will we need to change out blowers and ductwork too? Will that extra 10% be felt?

What say the experts?

[Dutch Star Don]

You don't say what year you're looking for. In 2024, Newmar FINALLY added a third AC to the 40' Dutch Star. There are older Newmar Mountain Airs in 40' that have three AC units. I believe back to may 2017 or 2018. They're a nice coach.

[wildtoad]

Swapping to 15k will not require changes to ductwork. Blowers are part of the AC unit.

IMO anything over 40' should have three units. Anything over 28 feet should have two.

[hastemaker]

We also live in "Gods Country" Bama & we also have a 40' RV that has two a/c units the one in the rear will freeze us in just a couple of minutes, but the front one has more room to cool so it takes a little more time, so if we need more front a/c we set a box fan in the rear pointed to the front...

[vito.a]

Your original A/C units are now 22 years old. They degrade over time.
Two new 15,000 btu A/C units will certainly help.
You will not need to upgrade duct work.
A 42' coach with a tag axle and three A/C units is nice upgrade.

[NXR]

We have a 38' gasser with optional dual pane windows. Yes, I know many DP's have them as standard and that's good. We have two 15K "equivalent" units and they will freeze us out in SW Florida in the winter but it only gets into the 90's in March, sometimes. We often only run just one in the 80's unless we're leaving the dog inside.

A less expensive fix is to get a thermal film applied to the windows. We're getting those added to our four sunroom skylights at home, which are 3' x 3', on Friday.

We're getting an "80% heat block/20% light" film added and I taped the sample to a sunroom skylight. When the direct sun is overhead, the carpet on the floor measures in the mid-90's but the small area on the carpet that is hit by the filtered light is only a few degrees above the places where there is no sunlight, if that makes sense. Low 80's. So we're seeing at least a 10F drop.

There are different films that can be added with different light transmission/heat blocking abilities. You could get some samples from a local place and just test them on the inside by holding them up.

I stood outside with the samples at the company and held them in front of my face in the direct sun to see which ones seemed to work the best.

For side windows you probably could go with a 50/50 film or a 60/40 film, which is about transparent.

We're getting an Llumar film: https://llumar.com/na/en/automotive/window-tint/

Some people just buy a roll of the stuff off Amazon and install it themselves. You probably could try that on a side window.


A MagneShade on the front windshield also works great but it can be a thousand dollars. It goes on the outside and is held on by strong magnets. There is a pole that lifts them into place. See : https://magneshade.com/

They also sell mirror covers and smaller shades for the driver area side windows.

People that have added a MagneShade to the windshield say it dropped the temp inside 10 to 20 degrees almost immediately. You can see out but no one can see in during the day.


Lots of options.

Ray

[hypoxia]

I had a similar need for more A/C capacity on my last 45' 3 A/C unit coach and found a 45' 4 A/C unit which has cured cooling problems.

Adding A/C capacity may require a larger generator and also affects AquaHot and clothes dryer usage due to the 50 amp limit.

[bamaboy473]

My goal is to stay under $80,000 just because I want to. We will never be full-time RVers so it will be like the boat; something to enjoy from time to time.

Pre-DEF seems to be the suggestion, so that brings us below 2008, right?

A 3rd A/C would then need a 42 minimum, and a tag would be the smart way to go to avoid too much weight on the rear axle.

I have found 2, but miles are huge (up to 200K miles) which is why I posted looking for a 40 with a 3rd unit.

Anybody have experience with ADDING a 3rd unit to a coach?

[OMMM4747]

If your rig isn't cooling enough there are things you can do to help get a little better performance.

Maintain your roof units. Clean the coils at leas 1x per year
Clean the inside filters 1x per month
Add a dehumidifiers (humidity in the rig makes it feel hotter)
Have a small personal fan or a larger tower/bladeless floor model
Keep window shades down
Get a windshield sun reflector
Deploy exterior shades
Park in the shade
Visit hot locations in the Spring or Fall

Good luck

[bamaboy473]

Does anybody with 3 A/C units experience too-warm conditions, assuming that the usual precautions are taken? Compare to your old 2-unit system?

[3pedal]

My parents have a 2018 40 foot Allegro RED with 3 ACs. It beats my Monaco with only 2 ACs when it gets hot. I would love to have a 3rd AC on mine when it gets real hot.

[Tony Ramirez]

! had a 37' w 2 roof AC's, between those & the dash AC it was comfortable. But the drive home thru the SoCal desert the one time when the dash AC went out was miserable for me driving, but the DW & dog were fine in the back of the coach.

This 41' has 3 roof AC's, can keep it pretty chilly.

[oldenavy]

We had a 38’ Tiffin Phaeton with 3 ACs. Never had any problems keeping it cool, except for how Tiffin placed the temp sensors. The wires for the middle unit ran inside the ducts and it would always read too low. Had to set that thermostat down about 8-10 degrees lower than the others or the middle unit would never kick on. Have had similar issues on other RVs, the manufacturers never follow the AC company’s guidelines on placing remote temp sensors.

[Gary RVRoamer]

My experience with 35-40 ft coaches with two (2) a/c units is that both run pretty much non-stop in 90+ weather conditions. There is a lot of variation dependent on sun loading on roof and walls, and covering skylights made a difference too. Humidity is a comfort factor too. My 40 foot American Tradition had two 13,500 btu heat pumps and those were barely adequate once the thermometer passed 90, only holding the interior to about 79. And of course, every time you open the entry door the a/c struggles to recover.


On sunny sites, deploying patio and window awnings is a noticeable help.