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  • Dual A/Cs, but only 1 seems to be blowing

    Good evening,
    Made the switch from a Jayco Octane to a 2021 GD Momentum G31. The coach came with 2 A/C units, which our Jayco only had 1 and it worked very well.

    This past weekend, we decided to take our G31 on a shakedown trip, in preperation for our 12 day trip in July. It is very hot in Florida, but we noticed it took an incredible amount of time to cool down. Both A/C units running, thermostat set to 76 and over the weekend the coach never got to 76 unless it was overnight. We have 1 A/C unit in the front bedroom and 1 in the living area, garage is separated but still ducted. I am pretty sure i have read that these two units are ducted together.

    Here is our issue: When both units are on, air blows through the vents but airflow is very weak, when the living area A/C is turned "off" the air still blows through the vents but once again very weak. When the bedroom unit is turned "off", no air comes out of the vents. I am sure this is something very simple but was wondering if anyone had any ideas?

    Thank you,

    Matt
    2021 GD G31
    2017 F-350

  • #2
    MadStella819 Matt, Welcome to the Family and the forum!

    I apologize for my lack of specific knowledge of your TT, but will work in generalities and if I am mistaken about something, both us get gained knowledge.
    First, there should be a second thermostat for the bedroom, and may be not activating the bedroom at the same time. This can be due to several different circumstances including settings and even uneven sunshine on one end or the other. Is the volume different with only either one is one and is it stronger with both on and all four dumps closed?
    Second, if you open the air dumps, do each of them have a strong flow or is it possible that one has the air coming out of the filters? One of mine had the baffle installed backwards and it was doing so.
    Third, does it make a difference if the filters are removed?
    Jerry and Kelly Powell, with Halo, Nash, Reid, Cleo, Rosie, and the two newest additions Shaggy and Bella..
    Nash County, NC
    2020 Solitude 390RK-R​

    Comment


    • #3
      Welcome to the forum, MadStella819 . I think you're correct that the two A/C units are ducted together, and that this ducting includes the garage. This can be confirmed with a tissue held up to the vents with at least the fans running on one or both of the units.

      Air flow through the vents is going to be weak compared to air flow through the dumps on the A/C units (For any newbies reading this, the dumps are the openings at the front and back of the A/C covering, They have a plastic damper that can be slid to the left or right to close or open the dumps). This is due to the size of the duct work compared to the size of the vents (A rant for another day), and the flow will decrease with distance from the A/C units (Also check the ducts for debris). Maximum flow through the vents will be with all dumps closed and both units operating.

      When we first had troubles with cooling our Momentum, I ran some basic calculations and determined that the A/C units were marginally sized to provide a 20 degree F temperature drop for the air volume of our trailer. So it becomes a matter of cooling management, trying to direct the cold air to where it will do the most good at the time. If the vents have moveable louvers, use them (Some have reported taping over vents with fixed louvers, or even replacing them) and close doors to direct the cold air where it is wanted and to keep it there. If the living room needs to be cooled, but the bedroom can be warmer, open the dump on the living room A/C, then close the dump and open the bedroom A/C dump to cool the bedroom down at night.

      Keep after it and I'm sure you'll find a system that works for you.
      John
      2018 Momentum 395M
      2018 Ram 3500 Dually
      Every day is a Saturday, but with no lawn to mow.

      Comment


      • #4
        Thank you guys, definitely a newbie to this site and posting on sites in general so I apologize as I try and explain better.

        I am familiar with dumps, vents, airflow, and thermostats but the ductwork and how it was configured between dual A/C units had me raising questions. to put it in a nutshell.

        if the front A/C unit is not running, there is zero and i mean zero air coming out of the vents throughout the entire coach. The air that does come out when both units are running could not really blow a tissue around. I am thinking that something is blocking the airflow from our galley A/C unit to the bedroom A/C, here is why.

        Air only blows when the front A/C unit is on. When i turn on the living area A/C, it runs but air does not blow from the vents, but does blow from the dumps on both units. i think there is something incomplete from the manufacturing process from the living area A/C to the front A/C.
        2021 GD G31
        2017 F-350

        Comment


        • #5
          I am pleased to announce that i can end this thread gracefully. Here is the solution:

          Our Momentum is equipped with the RV Airflow system that diverts air directly into the ducts. I did not have much experience with this system but after I read JBill's post I went to check on the living unit again. I noticed that it did not seem to make sense how it was mounted. From the factory, it was mounted upside down therefore covering the intake to the ductwork on each side of the unit. i loosened the 4 bolts, flipped it and it now works great. Thanks for the help, this forum is awesome.

          In the pic, the "square" is supposed to be on the top directing the airflow directly into the duct. In this picture, the configuration actually covered the intake to the ducts.
          2021 GD G31
          2017 F-350

          Comment


          • #6
            Originally posted by MadStella819 View Post
            Good evening,
            Made the switch from a Jayco Octane to a 2021 GD Momentum G31. The coach came with 2 A/C units, which our Jayco only had 1 and it worked very well.

            This past weekend, we decided to take our G31 on a shakedown trip, in preperation for our 12 day trip in July. It is very hot in Florida, but we noticed it took an incredible amount of time to cool down. Both A/C units running, thermostat set to 76 and over the weekend the coach never got to 76 unless it was overnight. We have 1 A/C unit in the front bedroom and 1 in the living area, garage is separated but still ducted. I am pretty sure i have read that these two units are ducted together.

            Here is our issue: When both units are on, air blows through the vents but airflow is very weak, when the living area A/C is turned "off" the air still blows through the vents but once again very weak. When the bedroom unit is turned "off", no air comes out of the vents. I am sure this is something very simple but was wondering if anyone had any ideas?

            Thank you,

            Matt
            Your statement indicates that your living A/C is not putting any air into the racetrac system. If you have the RV Airflow foam blocks in your A/C units from the factory I would check to be sure they are installed correctly. I know someone somewhere posted that theirs were installed upside down so there was no air going into the racetrack ducting.

            Another thing to consider, I think it was the Changing Lanes YT channel is that they analyzed their airflow out of the vents. They installed these 'half ball' things in the duct above the vents that caused an increased airflow out the vent by disrupting the airflow in the vent. But it seems to me you are getting NO air into the racetrack from your living A/C.

            You should also check the separator panel in the units. This separator splits the intake side from the cold air exhaust side. If the panel is out of wack, or even missing, then all of your cold air that should be going into the ducting is being sucked in by the intake and not entering the racetrack. This below link takes you to the Changing Lanes website. You can access the YouTube video there.

            https://changinglanesrv.com/rv-airflow/

            My money would be on your Airflow block is installed upside down if you have them.

            If you do not have them then your intake/exhaust separator may be out of adjustment. Here is a video from the My RV Works, Inc. channel where he explains very well the seperator.

            https://www.youtube.com/watch?v=rxCl...m7i4pL&index=6



            Mike & Lisa
            Central Florida
            2021 Imagine 2970RL
            1996 Chevy K3500 Crew SRW 7.4L Gas

            Comment


            • #7
              Originally posted by MadStella819 View Post
              I am pleased to announce that i can end this thread gracefully. Here is the solution:

              Our Momentum is equipped with the RV Airflow system that diverts air directly into the ducts. I did not have much experience with this system but after I read JBill's post I went to check on the living unit again. I noticed that it did not seem to make sense how it was mounted. From the factory, it was mounted upside down therefore covering the intake to the ductwork on each side of the unit. i loosened the 4 bolts, flipped it and it now works great. Thanks for the help, this forum is awesome.

              In the pic, the "square" is supposed to be on the top directing the airflow directly into the duct. In this picture, the configuration actually covered the intake to the ducts.
              You beat me to it. As I suspected - upside down. I think RV Airflow needs to stamp something useful on them like "If you see this side it is WRONG! THIS SIDE UP!" Might help the factory folks know which side goes up.
              Mike & Lisa
              Central Florida
              2021 Imagine 2970RL
              1996 Chevy K3500 Crew SRW 7.4L Gas

              Comment


              • #8
                MadStella819 -- can you please put the trailer's VIN in your profile? I'd like to pass on the issue found on your trailer to the appropriate person at Grand Design.

                Thanks. See the Welcome Letter if you're not sure how to post your VIN. https://gdrvowners.com/forum/main-fo...to-new-members

                Howard (Moderator)

                P.S. A reply when completed would be appreciated or I might forget to check!
                Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

                2017 Ford F-350 DRW, '19 315RLTSPlus

                Comment


                • #9
                  MadStella819 Glad you found the problem! Another rant (for another time) is the "racetrack" moniker and the airflow in a circle description.
                  Jerry and Kelly Powell, with Halo, Nash, Reid, Cleo, Rosie, and the two newest additions Shaggy and Bella..
                  Nash County, NC
                  2020 Solitude 390RK-R​

                  Comment


                  • #10
                    Originally posted by howson View Post
                    MadStella819 -- can you please put the trailer's VIN in your profile? I'd like to pass on the issue found on your trailer to the appropriate person at Grand Design.

                    Thanks. See the Welcome Letter if you're not sure how to post your VIN. https://gdrvowners.com/forum/main-fo...to-new-members

                    Howard (Moderator)

                    P.S. A reply when completed would be appreciated or I might forget to check!
                    VIN is in my profile sir, thank you.
                    2021 GD G31
                    2017 F-350

                    Comment

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