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Installing 3rd AC Unit on my 2015 38RESB3

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  • Installing 3rd AC Unit on my 2015 38RESB3

    Friends,

    Last night I ordered a Dometic Penguin II 13.5K BTU ductless AC unit and the lower duct and control unit for my RV. I'm going to remove the ceiling fan and use that electrical circuit for the AC unit. I believe this is the standard location for the third AC unit. We'll use it for supplemental cooling when very hot and quick cooling when getting set up. I did this on a 2000 Travel Supreme we had and it worked great. I see it working well here too. We're going on a short trip with friends this weekend and will be likely installing it next week. I'll post pics. This is a really easy upgrade for those interested in having a third unit.

    Just as an FYI: we purchased our unit off the lot in 2015 at a $50K discount, so there were a couple of features I would have ordered, if going that route. This one had the floor plan, the MorRyde IS and several other upgrades, the price mad it worth it. Since purchasing, I've added slide covers, sleep number bed, 6500W generator, storage slide in basement, entertainment syst in the basement, 70" smart TV when our 60" fell off the wall, replaced all lighting with LED. So, this should be the last upgrade for this unit.

    So, stay tuned,

    Ron
    2015 Mobile Suites 38RESB3 "Very Suite"
    2017 Ram 5500Laramie Crew Cab 4X4, 9' CM tow body

  • #2
    Curious why not a 15k unit?

    Here are the locations of the three AC's from the factory.

    Is your 6500 gen a 240V model?

    39TKSB3 "Highly Elited"

    2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's 37,500# GCVWR "Towing Beast" "HeavyWeight" B&W RVK3600

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    • #3
      I thought I would minimize current draw. I believe there is about 4amps difference between the two. After the fact, I could have checked with other MS owners to see the size of the 3rd unit installed at the factory.

      My 6500 watt gen is a 240 volt model.

      Ron
      Last edited by Wiredawg Chief; 10-03-2018, 10:00 AM. Reason: add gen comment
      2015 Mobile Suites 38RESB3 "Very Suite"
      2017 Ram 5500Laramie Crew Cab 4X4, 9' CM tow body

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      • #4
        Friends,

        All done. The unit installed fairly easy, I needed to get long mounting bolts; the 7 inch ones too short. Got 8 inch at my local RV supply. I dropped the ceiling fan, the mounting frame and voila, MS has a nice 14.25" frame in the ceiling that just happens to be the dimension for the AC unit. I drilled 4 holes all the way through the roof, 1 at each corner of the framed are from below. I then climbed up on roof, used straight edge and marker to mark outside screw holes. I also marked the rubber roof diagonal and cut the diagonal both ways with utility knife. I like folding the roof material into the hole for better seal. I then used my little Rockwell power saw... this is great for this type project. After carefully cutting roof out with saw, I applied some self leveling caulk under the flaps of roof membrane, and folded it into hole. Had to get my neighbor to help get AC unit on roof. I used 4" ratchet strap on AC unit still inside shipping material. I got on roof and pulled up and my neighbor pushed it up. Once on roof, I unboxed it, and placed it over hole per AC instructions. Went inside and installed the control unit. Even with the longer screws, I still had to position a clamp inside the AC unit and the control unit to draw them together. I installed the front two first and the rear one went in without the clamp. The MS ceiling fan wiring is 14 gauge, and this unit draws 15 amps, as verified with my power control center. Making wiring connections, and installing the control cover went without a problem. See pics. This took 6 hours to complete, 1 hour was travel time to get longer bolts. Anyway, it blows real cold and is real quiet. This is an easy project if you and a neighbor can get it on the roof and aren't scared to cut a hole in the roof of a $145K RV. Feel free to ask questions.

        Cheers, Ron

        2015 Mobile Suites 38RESB3 "Very Suite"
        2017 Ram 5500Laramie Crew Cab 4X4, 9' CM tow body

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        • #5
          and now the pics. Sorry, they're a little out of sequence. One more thing, I was amazed I received these today. Super fast and free delivery from Camping World. BTW, the unit I installed is the end one. I'm way tired.

          Bottom.jpgTop.jpgDuct.jpgTop-Open.jpgVise.jpg
          Last edited by Wiredawg Chief; 10-03-2018, 07:06 PM.
          2015 Mobile Suites 38RESB3 "Very Suite"
          2017 Ram 5500Laramie Crew Cab 4X4, 9' CM tow body

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          • #6
            Originally posted by Wiredawg Chief View Post
            I thought I would minimize current draw. I believe there is about 4amps difference between the two. After the fact, I could have checked with other MS owners to see the size of the 3rd unit installed at the factory.

            My 6500 watt gen is a 240 volt model.

            Ron
            All three AC's are 15A. You can only run two with the 6500 gen.
            39TKSB3 "Highly Elited"

            2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's 37,500# GCVWR "Towing Beast" "HeavyWeight" B&W RVK3600

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            • #7
              Curious what else is on you ceiling fan circuit?

              So the 13.5 even draws 15A?
              39TKSB3 "Highly Elited"

              2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's 37,500# GCVWR "Towing Beast" "HeavyWeight" B&W RVK3600

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              • #8
                Honestly, I was expecting around 11 amps. The 15KBTU pull ~ 15 to 16 amps. I was tired and didn't really check anything that might be pulling 4 amps. 12 Volt Converter? I'll follow up when I get a chance to analyze,
                2015 Mobile Suites 38RESB3 "Very Suite"
                2017 Ram 5500Laramie Crew Cab 4X4, 9' CM tow body

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                • #9
                  Originally posted by Wiredawg Chief View Post
                  Honestly, I was expecting around 11 amps. The 15KBTU pull ~ 15 to 16 amps. I was tired and didn't really check anything that might be pulling 4 amps. 12 Volt Converter? I'll follow up when I get a chance to analyze,
                  DRV is FAMOUS for overloading circuits! We added a 20A at each end of our island. So that's been great. The idiots thought it was fine to have EVERYTHING minus the Fireplace on one circuit from entry door thru off door slide across back and along entertainment center and along cooktop up to frig. I took the last outlet next to the frig and made it a 20A. I mentioned it to them at the Factory that I was constantly tripping that circuit but Ed "MR NO" said that was how they engineered it. Me tech was nice enough to give me a 20A breaker so I could deal with it my self!
                  39TKSB3 "Highly Elited"

                  2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's 37,500# GCVWR "Towing Beast" "HeavyWeight" B&W RVK3600

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                  • #10
                    Cummins12V98, You're right about the whole living room on single 15amp circuit. We're camping so turned on new AC, worked great, then turned on TV...breaker popped. Going to have to run a sperate 20 amp leg from the breaker box for the A/C. No problems prior to this with power, except last trip out, I was standing by the breaker panel and felt heat from it. I shut power at the park box, opened the panel and tightened each lug between a 1/4 and half turn. No more heat there. Anyway, this should not be hard to run another leg. This AC unit must be drawing 15 amps, BTW. Cheers, Ron
                    2015 Mobile Suites 38RESB3 "Very Suite"
                    2017 Ram 5500Laramie Crew Cab 4X4, 9' CM tow body

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                    • #11
                      VERY curious how you plan to get power from breaker box to the fan/AC location? I hope you are darn lucky and the wire comes all the way back to the panel, but not likely.
                      39TKSB3 "Highly Elited"

                      2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's 37,500# GCVWR "Towing Beast" "HeavyWeight" B&W RVK3600

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                      • #12
                        Yep, I know. I have some ideas. one, I believe the living room is fed from the belly. I think I can run another circuit from the from the breaker to the corner where the ceiling fan switch is. I can isolate the ceiling fan from the other plugs, upgrade the former ceiling fan switch to 20 amp rated one, and fish the new circuit up to the switch. Two, I may be able to fish a circuit from the new A/C unit, through the ceiling to the wall, where there is crown molding. I may be able to remove the crown molding and run the new circuit behind it, to the wall where the breaker panel is located. I can either fish the compartment where the break is or run a thin conduit in the corner to feed in the breaker.

                        I may call DVR and ask some advice about what they recommend. Won't hurt to ask. Enjoying South Padre Island for now. Cheers, Ron
                        2015 Mobile Suites 38RESB3 "Very Suite"
                        2017 Ram 5500Laramie Crew Cab 4X4, 9' CM tow body

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                        • #13
                          Your idea behind the crown moulding is the ticket!!! I don't think any visible wire mould would be needed. I think stranded 12/3 SO cord would be a good choice for it's flexibility.
                          39TKSB3 "Highly Elited"

                          2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's 37,500# GCVWR "Towing Beast" "HeavyWeight" B&W RVK3600

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                          • #14
                            Friends,

                            I haven't started the "run the new 12 gauge electrical circuit project" yet, but thought I would share info from the DVR factory: I told them I added a new 3rd AC unit and asked what is the best way to run a new circuit for it from the power panel to the unit. The DVR tech I spoke with recommends removing the 4 ceiling panels between the new AC unit and the power panel to run the new wires. I'll take DRV's recommendation under advisement.
                            The 4 panels between the new AC unit and the power panel have a lot hardware that has to be removed, including the the pretty decorative wood ceiling/lighting accent and the fantastic fan. I haven't ruled out running through ceiling and behind the crown molding, but like keeping modifications using factory practices.

                            I first want to kill the power to the RV and pull the power panel to see how the one 15 amp 14 gauge romex routes; either above through the ceiling, or more likely under the floor between the frame. If under the floor, my thinking is to run new 12 gauge wire same route as what I believe is the existing circuit, then see if I fish it up to the ceiling fan switch located on the far rear side wall next to the DS slide. Then see if I can remove just 2 ceiling panels to route it to the location. This route is cleaner for ceiling panel removal. I would like to upgrade the old ceiling fan switch to a 20 amp rated light switch and use it to turn the unit on and off. I never intended to use this unit except for quick cooling and when camping in 90 degree plus temps.

                            I have about 3 weeks for our next scheduled trip out and likely won't need the 3rd AC unit, but I'm a type A and am self driven to complete the project. I'll update as I progress with more pics.

                            Cheers, Ron
                            2015 Mobile Suites 38RESB3 "Very Suite"
                            2017 Ram 5500Laramie Crew Cab 4X4, 9' CM tow body

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                            • #15
                              I like to do things correctly but removing the panels is WAYYY overkill and could end ups with a damaged panel, then what!!! Plenty of room behind the crown moulding to run the SO 12/3 wire. I was known as the picky Superintendent! I never do anything half AZZ.
                              39TKSB3 "Highly Elited"

                              2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's 37,500# GCVWR "Towing Beast" "HeavyWeight" B&W RVK3600

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