Upgrading roof air conditioners

Since there hasn't been much "action" on the Forum lately (unless I'm looking in the wrong place), I thought I'd start a new thread to stir up some activity & kick some ideas around.

This whole issue came to the forefront last September when at/during the 2025 PC Reunion, down south in Louisiana and Mississippi. We live in SW Utah and our humidity hovers in the 12-16% range throughout the year. I was reacquainted with the humidity "issue" inroute, during & after the reunion. On our way, we visited with friends in Texas, just north or DFW. The AC ran 24/7 and we burned up a 20a adapter in the process. The breaker never tripped, but it sure did melt the adapter. Not good, and it was only discovered as we were packing up camp upon departure. UGG.
For the rest of the trip, we had 30a service at campgrounds, but one "thing" nagged at me. I had installed a soft start about a year prior, but that THUD persisted every time the compressor kicked on, often times waking me up in the middle of the night. Something needed to be done.
At the Natchez Reunion while discussing PC upgrades during a owners session, one of the members asked if anyone had changed out their A/C with an inverter model. We were (unfortunately) out of time, but he (I sure wish I remembered his name) invited me to see his upgrade in his PC. I was convinced! This inverter model was much quieter, definitely made the coach cool, reportedly draws ~ 1/2 the current of non-inverter models and seemed like the way to go. The only down side is that the unit runs continuously.
When I returned home, I began researching Inverter A/Cs.
Spoiler alert: I ended up changing out my 120VAC unit with an inverter unit AND, I also added a 12VDC unit in the sleeping area of our 3100.
Has anyone else done either or the same or might be considering a switch-out?
I added the 12VDC because Lucy & I prefer to boondock, when not attending events where AC is available.
I'll be back with what I experienced as soon as I get a better handle on how to add info to my thread.
Kirk

Kirk, I'm interested in this as well and I've done some research...


I have the original 15K btu Penguin in the middle of my 2900 that is now 16 years old and I worry how long it will last.  It draws 18 amps on high while cooling, 14.5 amps is just the compressor.   When it quits the next AC must be a lot more efficient, quiet, and if possible 18K or 20K btu.   


I've thought about switching to a 12V AC since I have 800AH of battery and almost 3KW of solar, which would work very well when boondocking with no power lost (and heat generated) to inversion.   When on shore power I would then pay the cost of converting to 12V for the AC.


However you touch upon a middle choice: Installing a 2nd AC and keeping the 120V AC.  The 12V could supplement the Ford AC on the road on the hottest days (with healthy solar collection) and while boondocking. I fear the rear AC would not cool the front of the coach well when parked no matter how many fans you place in the hallway, so the 120AC would need to run occasionally.


I admit I've looked at 12V AC units and what caught my eye are the split units. The inside unit would fit between the bedroom closets against the ceiling (I have a useless cabinet with a TV mounted on it there now), and the outside unit would fit under the coach beside the fuel tank.. Where it is nice and shady. It might also be easier to run the heavy duty 12V wires under the coach.


Here are a few reasons why I haven't pulled the trigger yet...


1  The Penguin hasn't died yet.
2. The invertor AC products that I've seen seen to have the thermostat inside the roof unit (Furrion is a good example of this). That's why they must continuously run. The airflow is needed so it can sense the room temp.  I do like the quiet when my Penguin auto shuts off between cooling cycles.
3.  My Penguin has a heat strip which is silent (except for the fan). It also work at any outside temp. I like that much better than a heat pump. Before August of this year, I've never seen a 12V AC with a heat strip, it's always a heat pump.   A couple weeks ago I read a sneak peak new product announcement for a 12V AC to be unveiled at the Hershey RV show (this week), and it mentionred a heat strip. Maybe they are listening to the RV community.
4.  Weight.... I'm always watching how much weight I add to my rig. I can add another AC, BUT, when I pull the specs on the units the weights really vary from 75lbs to almost 180lbs.  I'm not sure if I trust them, or if it is a case of quality is heavier, or sloppy marketing, or ???
5.  The split unit puts half of the weight below the floor, which appeals to the engineer in me, but it would require some shielding to block the dirty&mud from the tires. Not a blocker, but an additional consideration.


So... Sorry I don't have answers,,, but I got plenty of worries and questions  LOL


Keep us informed. Tell us how the new 12V works in summer and winter.


.Larry

Hi Larry,
First off; I thoroughly enjoyed co-hosting the Solar/LiPo4 battery conversion discussion we presented at last year's Natchez reunion.

Second; Thank you for joining the discussion.

To address the points of your reply.

1. I get it; if it works, don't fix it. A good rule to live by, but, in my case,  when the compressor kicking-on (even after adding the SoftStart) keeps you awake, that isn't "working" so I needed to remedy the probem. We had the original (2011 vintage) DuoTherm roof air. I didn't want to wait until it failed during a heatwave-usually, my luck.

2. Yes, having the thermostat/temp sensing unit inside could be improved upon, but that seems to be the state of the art right now, so other options did not seem available.

3. Heat strip: We have never used the heat strip on the Duo Therm. We prefer to use the FAU if we are awake (another noise issue) or a Little Buddy propane unit. We do not camp in very cold conditions, maybe only into the 20s, and we primarily boondock. The L'tl Buddy works very well. the only problem is deciding who will get up in the morning to turn it on:{)

4. I do not remember what the Duo Therm weighed, but I could guess that adding the 12v unit while replacing the DuoTherm, the additional weight was minimal. I had a MaxAir powered fan unit in the sleeping area. The 12VDC A/C unit I installed was 48lbs. I'd bet that there was a 20lb total increase in the weight on the roof. A concern, yes.

5. With the 12VDC unit, I only needed to route the 8ga wire down to the batteries(s). With a split unit, you would need to get the lineset routed between the under-floor unit and the roof unit. I dedided to go the easy way; a self contained roof unit. Also; is there a 12VDC RV split unit on the market?

Reference the 12VDC Install:
I routed the power cable across the roof, encasing it in electrical UV resistant Liquidtite to  my refrigerator vent, then down the back of the refer where I installed the circuit breaker, then through the floor and directly down to my battery bus bar which is mounted under the coach close to where the factory battery tray is. .  As it turned out, I needed 2 additional feet of cable to reach my busbar. I had some 4 ga lying around so used it for the extension.
The extension of the supplied power cable has stirred up many an internet conversation about how it should be dealt with, usually from owners of long 5th wheels who are installing the AC in a rear bedroom and supplying power from a front-mounted battery bank and the supplied cable would not reach. For us PC owners, that isn't really an issue. I have the 3100 and if I only needed an additional 2' of cable, those with smaller units should be fine. I'm sure, since this cable issue is resistance based, my addition will be fine.
I consider this is a DIY project, but it took me 2 partial days to complete, from the MaxAir removal, roof prep, getting the unit up on the roof, and installing the new AC.
There was another common stumbling block; the supplied bolts caused the interior ceiling  unit to project about an inch lower than snuggly fitting up against the ceiling. I just used the supplied bolts and put in some rubber gap trim. It looks/works fine.

EXPERIENCE: Our 2026 road trip involved a drive from SW Utah to Oshkosh, Wi. for the EAA Fly-in, July 20-27. Along the route we used the 12v unit extensively. Most of our camsites were off-grid, as was our campsite at the Fly-In airport, so the 12V unit was our primary cooling. It is super quiet in Sleep Mode and cools the sleeping area well. The unit is so quiet that it really does not block out all of the outside "noise," especially the low altitude military fly-bys as a wake-up call each morrning. 
When we did have shore power, we used the new 120VAC unit to cool down the coach, then switched to the 12VDC unit for nightime. The 120VAC unit  is also much quieter than the  15 year-old unit replaced, but the fan runs continuously. Reportedly, the current draw is about half that of a non-inverter unit, so when running the AC AND the microwave was an issue, installation of an inverter unit should quell that.

The new units also sport an included interior light, activated by the included remote control, which is very usable:
 
THE ROOF: The 12VDC unit is considerably lower than the 120VAC unit and the new Inverter 120VAC unit is the same height as the old DuoTherm, so any additional wind resistance isn't an issue.

WITH ALL OF THE ABOVE BEING SAID: We, like Larry have over 800 AH of LiPo4 batteries and 1000 watts of solar on the roof. The solar would charge the batteries fully during the day. After running the 12VDC unit all night, we still had 2/3 -3/4 charge on the battery bank. If anyone else with lesser battery storage is considering such, research using your AH capacity and current draw should be considered.

The inverter options that are available are a step up, if you should find a need to replace your current unit.

https://www.turbro.com/products/greenland-13500-btu-inverter-rv-air-conditioner-with-heat-pump?utm_campaign=GGPSZMZ&utm_source=google&utm_medium=cpc&gad_source=1&gad_campaignid=23984465691&gbraid=0AAAAABX_xBIPDIil-8blZ7sCflBvgKghP&gclid=Cj0KCQjwzsjVBhC3ARIsALnMv4mxeAGcTqBNYLXRXTCKTtX_fb482iCKabgKy_XaKNLGzXiXgms3xF8aAod8EALw_wcB


https://www.turbro.com/products/greenland-12v-dc-inverter-rooftop-rv-air-conditioner

I will post some pictures, as soon as I can locate my SD Card reader/adapter.
Kirk

Hey Kirk, I suspected that was you,,, it just didn't know your form name "Desert Dave".


Agreed, our workshop last year was a pleasure. The few minutes we had flew by, and the group interaction was excellent.


Sorry if I sounded like the 12v AC was a bad idea.... I'm all for it. I'm personally struggling with so many options it's truly rough to narrow down the best one for me.  I will add that I trust a heat stripp for those times I need to leave the heat on and step away from the RV.  I never do that with a portable heater.


Your usage pattern mirrors what many people do in a bricks and sticks home.  Cool the whole house during the day, and then switch to a smaller unit for the bedroom at night... for good reason.


I'm impressed you can run the 12 volt unit all night and still have 2/3rd to 3/4th battery remaining. I don't get that good of consumption rate with a 120V unit... But I'm also cooling the entire coach. The victron multiplus II generates a lot of heat inverting from 12v to 120v and that heat is wasted battery power.  After a sunny day on padre island, batteries full, and then AC thru the night, I had about 15 to 35% of battery left.   One day was very cloudy & muggy. My batteries were only 80% full at sunset and I ran out of juice before sunrise.   This past July my solar installers made some tweaks and so far I've been charging faster and using/moving power more efficiently... Not moving power from one battery pack to another as much reduces waste.  I'm eager to go boondocking for week again and see what the results are.


Side note:
I know the feeling on the furnace noise. I ended up putting a fireplace insulation blanket (faced ceramic wool rated for 2000F) around it and it blocks much of the noise, and stops the heat from heating the closet above. The coach stays warmer and more evenly now too.  Now I just hear the air from the vents, not the motor & fan in the furnace. I did a write up on this here in the forum a couple years ago.


The 12v split units I have found are not being marketed for RVs, instead they are very popular for the trucking and marine (think small yachts & large house boats) industries and offered as 12v and 24v units.  They are usually rated for 24x7 usage, ranging in btu sizes to cool a small cab to as big as a delivery box truck. I think the biggest single compressor unit I've seen was 20k btu,, but they also make double composite units.  I first found them watching a YouTube video on a semi cab that had a luxury RV coach instead of just a bed behind the driver's seat    I did see that Brinkley announced a new top of the line 5th wheel at Hershey this month with a double split units. The reviews are impressive and the "AC noise" is now outdoors and under the RV.


I forecast a big shift in AC technology in the RV industry as they scramble to keep up with innovation that is knocking down decades old barriers.  Specifically, 12v inverter compressors, high power brushless fan motors, huge battery capacities, larger solar power sources (plus maybe mobile wind power very soon), and modular split units.   ... Hence my hesitation to make a choice yet. If my penguin quits, I'm ready to replace. If it holds out a few more years I hope to benefit from an enlightened RV industry.


Good to hear from you again. Great topic!
Larry