How To Install a soft start in a Dometic roof top air conditioner

[redbaron]

Interesting! I'll revisit this again at Sparta and or Newmar again this fall. Try to sort out the over voltage draw. There is a Hughes Autoformer between the Shore Post and panel. Claims 120V+ at the receptacle?

If you have the HAF, then it is possible that the campground itself has very low voltage, causing your HAF to do its thing, which will increase amp load. I have found this to be true at one spot, but never consistently. I use a lot of power, including the OASIS electric burners, washer, dryer, tvs, laptops, etc...never once have I had to worry about it and never once has the 3rd air shutdown due to the EMS.

I suspect that maybe your coach is not balanced on the panel, which is one thing you can check by watching loads on L1 and L2, and see if they appear balanced.

Another thing that is different, as @Neal mentioned, I have always had the microair easy starts on my units. This does eliminate the hard spike that could trip a breaker under high load.

Check your balance first, as that is easy.

 

[Neal]

Keep in mind too that @Joe Hogan's setup is different than yours. His is more like mine with LiFePO4's, dual victron inverters, etc. and the pass through may be a different config. I think SES does the lithium installs for Newmar and the load shedding design, I believe, is different from the prior Magnum world.

 

[Joe Dutchstar]

I see nothing wrong with this. Its almost like when I would post somewhere that I drove 900 miles in a day in my dp, people would say, "thats not safe, you should only drive 300 max"
Who determines 300 miles is some kind of a limit? Some of us have stamina and abilities that others do not. Just like this car, its 100x safer then the cars were in the 60's/70's as are all cars these days. I have had everything from a 32 Ford to a Z06 to a top fuel dragster, I have no fear of my abilities but always respect the vehicle.
We can all have an opinion but who are we to judge who owns what. I am more scared of a dp when the driver gets out and cannot stand up straight and can barely walk at 85, but is driving a 50,000 lb missile.
JMHO

If you have the HAF, then it is possible that the campground itself has very low voltage, causing your HAF to do its thing, which will increase amp load. I have found this to be true at one spot, but never consistently. I use a lot of power, including the OASIS electric burners, washer, dryer, tvs, laptops, etc...never once have I had to worry about it and never once has the 3rd air shutdown due to the EMS.

I suspect that maybe your coach is not balanced on the panel, which is one thing you can check by watching loads on L1 and L2, and see if they appear balanced.

Another thing that is different, as @Neal mentioned, I have always had the microair easy starts on my units. This does eliminate the hard spike that could trip a breaker under high load.

Check your balance first, as that is easy.

Do you use the Bluetooth addon? If so, what does that provide?

 

[Neal]

Do you use the Bluetooth addon? If so, what does that provide?

Review this thread:

Question Thread 'Micro Air Easy Starts'

Jun 12, 2025

I was contemplating installing easy starts on the ACs in the coach . For those running them, a question. Do you think it's worth the $ if running on 50a 99% of the time? Just wanting to ease the load on the units.

• lostinfla
• Replies: 23
• Forum: Newmar Owners Club

 

[redbaron]

Keep in mind too that @Joe Hogan's setup is different than yours. His is more like mine with LiFePO4's, dual victron inverters, etc. and the pass through may be a different config. I think SES does the lithium installs for Newmar and the load shedding design, I believe, is different from the prior Magnum world.

How does that affect anyting when using shore power? It shouldn't---and if anything, it will be a better position to give inverter assist.

Lithium and inverters are usually not used during shore power connection.

 

[redbaron]

Do you use the Bluetooth addon? If so, what does that provide?

No, I see no reason for the bluetooth addon.

 

[Neal]

How does that affect anyting when using shore power? It shouldn't---and if anything, it will be a better position to give inverter assist.

Lithium and inverters are usually not used during shore power connection.

I don't know but I would definitely have Newmar check this out on the next visit. Looking forward to hearing what the find is but I'm still learning my setup and wonder if it's the LiFePO4 and inverter config that is a bit different from what we know in the past Newmar design. I could very well be completely wrong so ignore everything after Bonjour from me

 

[Neal]

Lithium and inverters are usually not used during shore power connection

Bonjour

I think in the LiFePO4 setup, more so the Dual Victron setup, everything passes through the Inverters and it can offer power assist, i.e. on a 30A shore power connection the coach can still see 50A as it pulls from the batts.

 

[Jonf254]

If Furrion made a rooftop unit that would be a drop-in for a Dometic Heat Pump...and CCC2 thermostat system which we already have...I'd try it. Our Domestic system has up invested in the fact there is an extra control board in our basement that connect to the AutoGenStart...so, the added benefit is pretty darned good --- esp if dry camping at races or air shows. We upgraded our thermostat (still CCC2 compatible) to the MicroAir EZ touch RV...and it connects to wifi. We can control our coaches thermostat from a smart phone app... which lets us turn the system OFF/ON, change basically anything on the thermostat that you could if you were standing in the coach. I use this to save on Genset use while we are out for the day...then reset the A/C thru the app --- generator will start, and cool down the coach before we get back. I'm hooked...can't give that up.

We also spend a lot of time in campgrounds...so honestly --- I don't get a discount for using a low amp A/C unit... although that would be a good thing when we store the coach at home. We keep the unit cool for humidity purposes...and it does bring our electric bill up substantially.

Yes I would agree having the remote access is nice.We boon dock allot and provide most of our own electric, having a 18k Air conditioner that runs on 1450 watts is critical for us to through the night and cloudy non travel days.Seems Theres always a trade off in the RV life

 

[Joe Dutchstar]

Bonjour

I think in the LiFePO4 setup, more so the Dual Victron setup, everything passes through the Inverters and it can offer power assist, i.e. on a 30A shore power connection the coach can still see 50A as it pulls from the batts.

I'll try the Newmar Mobile Tech to see if I can solve this for this summer weather. Tech is scheduling for July 22. Let you know what he finds out.

 

[Neal]

I'll try the Newmar Mobile Tech to see if I can solve this for this summer weather. Tech is scheduling for July 22. Let you know what he finds out.

I'd use caution there, it may be worth a call into the DSDP hotline to see what they say. Either way, interested to see what you learn.

 

[redbaron]

Bonjour

I think in the LiFePO4 setup, more so the Dual Victron setup, everything passes through the Inverters and it can offer power assist, i.e. on a 30A shore power connection the coach can still see 50A as it pulls from the batts.

true--so it should be better than without---like I said---without it this isn't a problem, so if the setup is now failing, either a configuration / design issue exists with the inverter setup, or the loads are not balanced, etc.

the max draw is 50A per leg, with nominal draws around 45A for continuous loads. This should be easily handled when connected to a shore power connection of 50A, and not cause power to drop.

 

[redbaron]

Joe: The simple test is the load balance test I mentioned. Regardless of how you are getting power, the panel will be where the balance is determined. If for some reason the 3 AC's are all on L1 or L2, then that would explain the issue. This is a free, easy test and will help eliminate a major possibility of why you are having a problem.

 

[MemoriesByTheMile]

Joe: The simple test is the load balance test I mentioned. Regardless of how you are getting power, the panel will be where the balance is determined. If for some reason the 3 AC's are all on L1 or L2, then that would explain the issue. This is a free, easy test and will help eliminate a major possibility of why you are having a problem.

This simple test ^^^^^^, if it shows all 3 roof top A/Cs are one leg, also has a relatively inexpensive fix, just having some breakers moved around.

We don’t have a DS, but we do have a coach with 3 roof top units (15k BTUs each) and all three run at the same time (they do have delayed starts). This is in addition to all the other electric goodies like the residential fridge, oasis, TVs, computer, router, etc.

 

[Chuggs]

I can't make sense of it. I manage to run two A/C's off a single leg of 30A divided to both A/C's. I do have the MicroAir Soft start on both units. When running they pull less than 14A. So...if you are in a 50A shore power connection, and the panel is balanced...you should easily run four units... It makes me wonder...are your units in need of coil cleaning? Is there a time delay for start? Is the thermostat malfunctioning and not staging the compressor starts? Is you power control system flaking out... I would just take some meter readings to see if they correlate to what the PCS is saying. Is the shore power voltage low...like 110v or lower vs 120v. Appliances use watts...so is line voktage is low...the amperage draw will need to go up to do the same amt. of work.