Adding 3rd a/c to factory prepped unit

[firemarshalbill]

The Texas heat is coming! Has anyone had a third a/c successfully added to their garage on a unit that came prepped for it from the factory? What all is involved? The more research I do, the more confused I get. The more answers i get, the more questions I have. According to the build sheet the unit is prepped for a 3rd a/c but apparently that doesn’t include the EMS. Some are of the opinion it’s no longer necessary on 2020 models. Hearing also that if the existing 2 units are wired to one leg of the breaker panel, that the 3rd unit should be pre-wired on the opposite leg and that you can plug and play. Have also heard the added unit will have its own EMS built in. Need expert advice here as this needs to be done sooner than later. Just can’t get a straight answer on how it needs to be done. The how determines the cost. Was told by dealer to add EMS system to make everything work correctly could cost upwards of $5K 😳. There has to be an easier way, especially if I’m prepped for it already.

Momentum 320G

[xrated]

I added another A/C unit to a different brand trailer a few years back that was prepped from the factory. The wiring was all there....120VAC, 12VDC, and the 4 conductor cable to hook up a separate wall thermostat. In my situation, the first thing was the removal of the existing roof vent. Roof vents have the same opening dimensions as the A/C units...approx. 14" square. Once that was removed, it exposed all the wiring mentioned above and it was a matter of lifting the new unit to the roof of the trailer and putting it on the existing opening. After that, connecting the 120VAC at the proper place, the 12VDC at the proper place, and then connecting the 4 conductor cable for the new thermostat on the wall. With Keystone, they dead-ended the other end of the thermostat cable in the wall at a location where they would normally mount a thermostat if it was installed from the factory.....but it took a little bit of work/searching to find that end of the cable inside the existing wall. I had to remove a couple of switches on that wall, use a mirror and flashlight to be able to see inside the wall. Once I located the end of the 4 conductor cable, I used a metal coat hanger with a hook bent onto the end of it to reach in and fish it out of an opening that I had made for the wire....where I was going to install the new thermostat, then hook it up. The other option, which I chose NOT to do, is to order an A/C unit that had all the controls on the A/C unit itself. Those type units require getting a step stool or ? to be able to change any setting....On/Off, Fan speed, cooler/warmer, etc. So to me, the obvious choice was to buy an addition thermostat that is completely independent of the others in the trailer. And you are correct, that next A/C does need to be on the opposite line from the other two. You should end up with two A/C units on one 120V line.....and the other one on the other 120V line. This is usually done at the factory when they prep for a third A/C unit, but it bears checking to make sure.

[mraplx]

I just added a third 15k unit to my Solitude 377MBS. Overall not that big of a deal, find a suitable location, cut a hole, add blocking for support, run Romex / thermostat wire, and bobs your uncle. Since yours is setup for a third unit it will be a very simple install. I do not have the EMS system and my setup works well. I will add I have to “manage” the setup myself if not on 50amp service. We just tested it this weekend, 103f no shade out and the trailer was at 71 inside. We’ll see how it does in the dead of an AZ summer, but should be much better than just two units running. Took about 1k in parts and 9 hours to install.


On a side note 2 of the units are on one 50amp leg and the other AC is on the 2nd leg.


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[FT4NOW]

I just added a third 15k unit to my Solitude 377MBS. Overall not that big of a deal, find a suitable location, cut a hole, add blocking for support, run Romex / thermostat wire, and bobs your uncle. Since yours is setup for a third unit it will be a very simple install. I do not have the EMS system and my setup works well. I will add I have to “manage” the setup myself if not on 50amp service. We just tested it this weekend, 103f no shade out and the trailer was at 71 inside. We’ll see how it does in the dead of an AZ summer, but should be much better than just two units running. Took about 1k in parts and 9 hours to install.


On a side note 2 of the units are on one 50amp leg and the other AC is on the 2nd leg.


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Sorry...I gotta ask. Bobs your uncle ???

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[mraplx]

Similar to, “and there you have it”


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[Nettles]

Please tell me you have install insight? I want to do this some kinda bad to our 18. Do you have install pics?