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Remember to Torque Check your A/C Mounting bolts

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  • Remember to Torque Check your A/C Mounting bolts

    Just a friendly reminder to torque check your A/C mounting hardware to prevent any leaks from a loose gasket. My 297RSTS is nearly 2 years old and I just torqued the mounting bolts and they were very loose. Lucky I didn't have a leak yet. Per the Dometic installation instructions torque is 4.5-5.5 N-m or 40-50 in-lbs. Since mine were so loose and not leaking decided to torque to 4.0 N-m or 35 in-lbs. I did buy a special 1/4" torque wrench a while ago to do this off of Amazon.

    Rob
    Rob & Barb
    2022 RAM 3500 Big Horn, 6.7 Cummins HO/Aisin
    2022 Solitude 378MBS

  • #2
    Yeah - the guy in the Momentum next to us got rain blowing sideways (during the tropical storm Tuesday) in through the AC gasket on his front AC because it was loose. The leak had some water dripping our in the bedroom around the AC.

    Rob
    Rob & Laura
    U.S. Army Retired (Rob)
    2012 F350 DRW CC Lariat PS 6.7, PullRite OE 18K
    2020 Solitude 310GK-R, MORryde IS and disc brakes, solar, BB LiFePO4, DP windows
    (Previously in a 2016 Reflection 337RLS)
    Full time since 08/2015

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    • #3
      I just recently got an inch pound torque wrench. Checked the a/c mounting bolts this morning , never been checked in the 3 years of ownership. All 4 bolts took around 8 or 10 turns to get to 40 inch pounds of torque. I believe the recommended torque is 30 to 50 inch pounds , TucsonJim has posted in another thread. I wish that I would have checked when purchased new but did not know to do that then. Also I am not sure if there would have been any "settling" in the gasket material over the years. We did not experience any leaks that entered inside the trailer. As loose as they were it is a wonder that the unit did not blow off the roof.

      Brian
      Brian & Michelle
      2018 Reflection 29RS
      2022 Chevy 3500HD

      Comment


      • #4
        Originally posted by Calbar View Post
        Just a friendly reminder to torque check your A/C mounting hardware to prevent any leaks from a loose gasket. My 297RSTS is nearly 2 years old and I just torqued the mounting bolts and they were very loose. Lucky I didn't have a leak yet. Per the Dometic installation instructions torque is 4.5-5.5 N-m or 40-50 in-lbs. Since mine were so loose and not leaking decided to torque to 4.0 N-m or 35 in-lbs. I did buy a special 1/4" torque wrench a while ago to do this off of Amazon.

        Rob
        Rob,

        This is great advice and I will check my bolts as well. But why did you not set the torque to the nominal setting of 45 in-lb? This would be the proper setting.

        Jim

        Comment


        • #5
          Guest

          Jim,
          Where is the reference for the 45 in-lbs? In the Airxcel 48000 Service AC Mach 15 Installation Instructions document in my files there's no reference to a torque setting. For the Coleman Mach 15 there's an "indication tab" (which I've never looked for...so will have to investigate). See snip from manual below.

          Click image for larger version  Name:	bolt tension.JPG Views:	0 Size:	127.4 KB ID:	29534
          Last edited by howson; 09-12-2020, 12:37 PM.
          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

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          • #6
            howson - The OP was referencing the Dometic AC units which have a torque requirement. You are correct that the Coleman Airxcel have their own torque methods. Also, if any of you original GDRV owners have an Atwood AC, the torque value for those is 5.2 ft-lb, or 62.4 in-lb.

            Jim
            Jim and Ginnie
            2024 Solitude 310GK
            GDRV Technical Forum Moderator
            GDRV Rally Support Coordinator

            Comment


            • #7
              Originally posted by MidwestCamper View Post

              Rob,

              This is great advice and I will check my bolts as well. But why did you not set the torque to the nominal setting of 45 in-lb? This would be the proper setting.

              Jim
              Jim,

              I decided to use the low end of the torque since I did not have a leak yet on the A/C and did not want to do full compression on the gasket. This gives me some additional torque and compression as time passes should I need it. My thought process was to allow for future re-torques without hopefully replacing the gasket.

              Rob
              Rob & Barb
              2022 RAM 3500 Big Horn, 6.7 Cummins HO/Aisin
              2022 Solitude 378MBS

              Comment


              • #8
                Originally posted by Country Campers View Post
                I just recently got an inch pound torque wrench. Checked the a/c mounting bolts this morning , never been checked in the 3 years of ownership. All 4 bolts took around 8 or 10 turns to get to 40 inch pounds of torque. I believe the recommended torque is 30 to 50 inch pounds , TucsonJim has posted in another thread. I wish that I would have checked when purchased new but did not know to do that then. Also I am not sure if there would have been any "settling" in the gasket material over the years. We did not experience any leaks that entered inside the trailer. As loose as they were it is a wonder that the unit did not blow off the roof.

                Brian
                Hi Brian,

                Yes mine took about the same number of turns. Really shocked me that it took that many turns to get close to the torque recommended by Dometic. Will check it again either before winter hibernation or in the spring to see if it settles.

                Rob
                Rob & Barb
                2022 RAM 3500 Big Horn, 6.7 Cummins HO/Aisin
                2022 Solitude 378MBS

                Comment


                • #9
                  Originally posted by MidwestCamper View Post

                  Rob,

                  This is great advice and I will check my bolts as well. But why did you not set the torque to the nominal setting of 45 in-lb? This would be the proper setting.

                  Jim
                  A caution on this . . . the spec torque is for new installation on new seals. I expect that seals that have been in place and conformed to the surfaces on each side will seal at far less torque . . . which is why many owners (including me ) do not have leaks at what is likely a much lower bolt torque.

                  Rob
                  Cate & Rob
                  (with Border Collies Molly & Angel + Kitties Hazel & Elsie)
                  2015 Reflection 303RLS
                  2022 F350 Diesel CC SB SRW Lariat
                  Bayham, Ontario, Canada

                  Comment


                  • #10
                    Originally posted by Cate&Rob View Post

                    A caution on this . . . the spec torque is for new installation on new seals. I expect that seals that have been in place and conformed to the surfaces on each side will seal at far less torque . . . which is why many owners (including me ) do not have leaks at what is likely a much lower bolt torque.

                    Rob
                    Well its a little too late now. Should I back them off and re-torque to a lesser amount?

                    Brian
                    Brian & Michelle
                    2018 Reflection 29RS
                    2022 Chevy 3500HD

                    Comment


                    • #11
                      Originally posted by Country Campers View Post

                      Well its a little too late now. Should I back them off and re-torque to a lesser amount?

                      Brian
                      I would not back off the torque once you have tightened the bolts. My point was that less than "spec torque for compressing new seals" is probably still OK for seals that were torqued to spec when new.

                      Rob
                      Cate & Rob
                      (with Border Collies Molly & Angel + Kitties Hazel & Elsie)
                      2015 Reflection 303RLS
                      2022 F350 Diesel CC SB SRW Lariat
                      Bayham, Ontario, Canada

                      Comment


                      • #12
                        Originally posted by Calbar View Post

                        Jim,

                        I decided to use the low end of the torque since I did not have a leak yet on the A/C and did not want to do full compression on the gasket. This gives me some additional torque and compression as time passes should I need it. My thought process was to allow for future re-torques without hopefully replacing the gasket.

                        Rob
                        Rob,

                        If the torque spec is from 40-50 in-ft the proper torque would be the nominal value of 45 in-lb. At a minimum you should be at the minimum torque spec of 40 in-lb.

                        Jim

                        Comment


                        • #13
                          Originally posted by Cate&Rob View Post

                          A caution on this . . . the spec torque is for new installation on new seals. I expect that seals that have been in place and conformed to the surfaces on each side will seal at far less torque . . . which is why many owners (including me ) do not have leaks at what is likely a much lower bolt torque.

                          Rob
                          Rob,

                          Understand that there may be a difference where a call to the manufacturer may be necessary to understand if the gasket just keeps compressing over time. A one time nominal torque that is designed to take compression into account on a new gasket makes sense. You would think the manufacturer would give some feedback on this. I believe I would still tighten to the minimum spec though.

                          Made some other minor Imagine repairs today in preparation for an upcoming trip to PA at the end of the month and had to replace brakes on my truck on all four corners. Amazing how $550.00 can disappear so fast. But they are sooo nice.

                          Jim

                          Comment


                          • #14
                            Originally posted by MidwestCamper View Post

                            Rob,

                            Understand that there may be a difference where a call to the manufacturer may be necessary to understand if the gasket just keeps compressing over time. A one time nominal torque that is designed to take compression into account on a new gasket makes sense. You would think the manufacturer would give some feedback on this. I believe I would still tighten to the minimum spec though.

                            Made some other minor Imagine repairs today in preparation for an upcoming trip to PA at the end of the month and had to replace brakes on my truck on all four corners. Amazing how $550.00 can disappear so fast. But they are sooo nice.

                            Jim
                            Jim,

                            I was thinking about that last night too. I think I will call Dometic tomorrow and see what they say. I will update the post with the info.

                            Yes very easy for $550 to vanish.

                            Rob
                            Rob & Barb
                            2022 RAM 3500 Big Horn, 6.7 Cummins HO/Aisin
                            2022 Solitude 378MBS

                            Comment


                            • #15
                              Originally posted by Calbar View Post

                              Jim,

                              I was thinking about that last night too. I think I will call Dometic tomorrow and see what they say. I will update the post with the info.

                              Yes very easy for $550 to vanish.

                              Rob
                              Rob,

                              Thank you. The other Rob brings up a great point where a one time torque that takes gasket compression into account makes sense. I would hope they did their homework and know just how far the gasket will compress over time and the first torque would take care of this. But how do we know the first torque was done properly?

                              Interesting topic.

                              Jim

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