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  • No AC/Furnace and Blank Thermostat

    I have a 2018 350M. We had an issue with power at the campground (there was a bad neutral to the pedestal). We discovered it when we powered up and the lights flickered and there was a buzz at the breaker box. We immediately powered down and switched to the generator. Everything works fin on the generator except the living room t-stat is blank - so no ac or furnace. The park power has since been fixed.

    We have a new battery. We have a new converter. No fuses that I can see appear to be blown. I swapped the t-stat with the one in the bedroom. Both work fine in the bedroom. Neither works in the living room. I need to know where the power comes from that feeds the thermostat. I have pulled apart every cabinet and looked at all the wires I can see and I can't see what feeds it. I thought perhaps it was fed power from the ac unit and swapped out that control box but no luck. Does the power come from the furnace or directly from the battery. Am I missing a fuse somewhere? I have checked all of them in the main breaker box at the bottom of the pantry and every one I can see in the storage area.

    HELP! I am frustrated. Thank you

  • #2
    Originally posted by BadPosse View Post
    I have a 2018 350M. We had an issue with power at the campground (there was a bad neutral to the pedestal). We discovered it when we powered up and the lights flickered and there was a buzz at the breaker box. We immediately powered down and switched to the generator. Everything works fin on the generator except the living room t-stat is blank - so no ac or furnace. The park power has since been fixed.

    We have a new battery. We have a new converter. No fuses that I can see appear to be blown. I swapped the t-stat with the one in the bedroom. Both work fine in the bedroom. Neither works in the living room. I need to know where the power comes from that feeds the thermostat. I have pulled apart every cabinet and looked at all the wires I can see and I can't see what feeds it. I thought perhaps it was fed power from the ac unit and swapped out that control box but no luck. Does the power come from the furnace or directly from the battery. Am I missing a fuse somewhere? I have checked all of them in the main breaker box at the bottom of the pantry and every one I can see in the storage area.

    HELP! I am frustrated. Thank you
    When I installed my front AC there was a 12V wire included in the ceiling bundle along with the thermostat wire and yellow Romex. The Romex was obviously the 120v, and the thermostat wire went to the thermostat and tied into the control box. I thought the 12v wire was for a ceiling fan, but figured out it's also there to supply 12v to the thermostat, it does not get it from the AC unit. I assume that is fused somewhere upstream, I'd think in the main fuse panel but I've never looked further than that.

    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.

    Neil Citro
    2018 Reflection 28BH Pepwave
    2019 F350 6.7L Long Bed Crew Cab

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    • #3
      There may be a fuse behind the touch panel, where the switches are that operate the slides or awning. Not sure what you have for this.

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

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      • #4
        Originally posted by Country Campers View Post
        There may be a fuse behind the touch panel, where the switches are that operate the slides or awning. Not sure what you have for this.

        Brian
        I have the MyRV Touchscreen in my pantry. There is a fuse behind that? My main breaker box/fuse panel is in that cabinet on the floor.

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        • #5
          Originally posted by BadPosse View Post

          I have the MyRV Touchscreen in my pantry. There is a fuse behind that? My main breaker box/fuse panel is in that cabinet on the floor.
          I am not sure that there is a fuse behind the Touchscreen, I would guess not. There have been fuses found behind the regular panels like I have in my model.

          Sorry for the confusion.

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

          Comment


          • #6
            What model thermostat, AC, and furnace?
            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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            • #7
              Originally posted by howson View Post
              What model thermostat, AC, and furnace?
              Coleman Mach for the AC and AirXcel for the t-stat. I’m not sure about the furnace. I will have to check on that.

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              • #8
                Originally posted by BadPosse View Post
                Coleman Mach for the AC and AirXcel for the t-stat. I’m not sure about the furnace. I will have to check on that.
                After reviewing Airxcel (Coleman/Mach) and Dometic's installation manuals, the reason the manufacturer is important to know in this situation is how 12v is supplied to the AC control box. In Dometic systems, 12v comes from the A/C control box to the thermostat. In Airxcel, 12v is supplied from the thermostat to the A/C (and furnace).

                Re-reading the initial post you are on the right track--find where 12v comes from to feed the living room thermostat. A typical wire diagram for an Airxcel is below (yours may be slightly different depending on the specific model of thermostat).

                Click image for larger version  Name:	diagram.JPG Views:	0 Size:	41.8 KB ID:	85958

                In the bedroom of my 315RLTS, the power for the thermostat junctures off of the light wall switch (pic below).

                That's not much help for the kitchen issue...and I'm not familiar with the exact location of the thermostat in the 350M so can't suggest where to look. However it should give you an idea of where to start--look for power on the Red and Blue lines coming into the thermostat. Based on the scenario it won't be there, so finding where it comes from will be CSI work.

                Please let me know if this helps (or doesn't). Note I'll be off the forum for the majority of the day so one of the other regulars here may jump in with further input to any response.

                Howard

                Click image for larger version  Name:	pwr.JPG Views:	0 Size:	95.1 KB ID:	85959
                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
                  When your issue is repaired please consider purchasing a surge protector for plugging in at the pedestal. One may have saved you this issue. There are many styles to choose from: https://www.rvweb.net/best-rv-surge-...tors-reviewed/ Good luck going forward.

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                  • #10
                    Originally posted by howson View Post

                    After reviewing Airxcel (Coleman/Mach) and Dometic's installation manuals, the reason the manufacturer is important to know in this situation is how 12v is supplied to the AC control box. In Dometic systems, 12v comes from the A/C control box to the thermostat. In Airxcel, 12v is supplied from the thermostat to the A/C (and furnace).

                    Re-reading the initial post you are on the right track--find where 12v comes from to feed the living room thermostat. A typical wire diagram for an Airxcel is below (yours may be slightly different depending on the specific model of thermostat).

                    Click image for larger version Name:	diagram.JPG Views:	0 Size:	41.8 KB ID:	85958

                    In the bedroom of my 315RLTS, the power for the thermostat junctures off of the light wall switch (pic below).

                    That's not much help for the kitchen issue...and I'm not familiar with the exact location of the thermostat in the 350M so can't suggest where to look. However it should give you an idea of where to start--look for power on the Red and Blue lines coming into the thermostat. Based on the scenario it won't be there, so finding where it comes from will be CSI work.

                    Please let me know if this helps (or doesn't). Note I'll be off the forum for the majority of the day so one of the other regulars here may jump in with further input to any response.

                    Howard

                    Click image for larger version Name:	pwr.JPG Views:	0 Size:	95.1 KB ID:	85959
                    We appear to have the same airexcl thermostat. So looks like I will be spending my lo mg weekend tracking wires.

                    Comment


                    • #11
                      Originally posted by TNFSolitude View Post
                      When your issue is repaired please consider purchasing a surge protector for plugging in at the pedestal. One may have saved you this issue. There are many styles to choose from: https://www.rvweb.net/best-rv-surge-...tors-reviewed/ Good luck going forward.
                      We have one

                      Comment


                      • #12
                        Originally posted by howson View Post
                        That's not much help for the kitchen issue...and I'm not familiar with the exact location of the thermostat in the 350M so can't suggest where to look. However it should give you an idea of where to start--look for power on the Red and Blue lines coming into the thermostat. Based on the scenario it won't be there, so finding where it comes from will be CSI work.
                        Click image for larger version

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ID:	86044

                        So the closest twelve volt items to the thermostat are the Touchscreen, the light in the pantry closet which is farther than the touch screen but is a push light, and the under cabinet lights. All of which have power.
                        Last edited by howson; 05-25-2022, 06:54 AM. Reason: Trimmed quote...(make response easier to read)

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                        • #13
                          Originally posted by BadPosse View Post
                          So the closest twelve volt items to the thermostat are the Touchscreen, the light in the pantry closet which is farther than the touch screen but is a push light, and the under cabinet lights. All of which have power.
                          So the task is to figure out where GD tapped 12V power for the thermostat and why the power is missing. It's going to take some troubleshooting to figure it out. If our trailers were wired consistently and there were schematics this would be much easier, but that's not the case.

                          If electrical troubleshooting is not something you're comfortable with doing it may be time to hire a professional. (Sorry--wish I could be more help.)
                          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


                          • #14
                            Just to update. I fixed it. The thermostat gets its 12v from the furnace. So I tracked the furnace fuse and it was good. Took the furnace panel off and I had 12v coming in to the control panel and the switch. Followed the wires out of the switch to behind the water heater. From there they switch colors and went for a bit until I came to some wire nuts. The positive was disconnected from the wire nut. It must have pulled out when I opened the panel in the storage compartment to check my converter fuses when I had the power surge. Re-wired them and the thermostat kicked right on and I’m happily cooling again. Thank you!

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                            • #15
                              Originally posted by BadPosse View Post
                              Just to update. I fixed it. The thermostat gets its 12v from the furnace. So I tracked the furnace fuse and it was good. Took the furnace panel off and I had 12v coming in to the control panel and the switch. Followed the wires out of the switch to behind the water heater. From there they switch colors and went for a bit until I came to some wire nuts. The positive was disconnected from the wire nut. It must have pulled out when I opened the panel in the storage compartment to check my converter fuses when I had the power surge. Re-wired them and the thermostat kicked right on and I’m happily cooling again. Thank you!
                              It is hard to believe that they put "hidden" wire nuts in these RV's, sure makes finding an electrical problem harder than it needs to be. Glad you found the issue.

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

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