R27 luxury edition -air conditioner cabin air sensor issues

[Jcat2010]

In case anyone else has had similar issues..our controller panel never registering the "correct" temp of the cabin as the "air" temp. After crawling into the quarter berth, and digging around, I located the return air sensor all nice and cozy, in a bundle of wire up against the hull. It is supposed to be located in the return grill, where it can sense the returning cabin air. It wasn't sensing anything but the hull temp where I found it. I unbundled and relocated it to just inside the return grille. Now get much better control now. While I was in there, I also closed up some gaps in the monkeyfur panels, gaps large enough to bypass the return, and also found a few holes cut in the fiberglass next to the main rectangular air supply duct that were allowing supply air to be pulled right back into the return and sealed them also. I still think there's quite a bit of return air bypassing the return filter, but that will be next year's project.

 

[scgck]

Our 2021 R27 LE also exhibits poor temp control in the heat mode.
It also cycles off way before selected temp is reached which leads me to believe something else in the system is shutting it down. It runs for about 10 minutes before the compressor cycles off for maybe 5 minutes.
Despite my best efforts the fan seems to only run at high.
It does a good job heating the boat when it runs although noisy and pulling about 100 amps DC from the house.
I will check the location of the sensor the next time I'm at the boat.
Thanks for the information.
Chris

 

[DMD3]

Not a real big inconvenience but I experience similar. Any chance you took pics? I’d like to have a look and see myself on our 27 LE.

 

[Jcat2010]

I did take pictures, if someone points me at where and how I can post, I'd be glad to. Not sure it will be the same on each boat, as I have see a few variations regarding the AC.

I'll describe as best that I can. Once in the quarter berth, go forward and remove the return grille. Once you have that out, if you shine a light up and toward stern, above the monkey fur panels, you should see an electrical junction box - mine was white. Coming out of that there should be a gray bundle of (maybe 22 GA) wire with a yellow heat shrink section on the end, maybe 3 inches long. That's the sensor. If you remove the sternmost monkeyfur panel above the berth, you might get better access. I had to remove mine and reposition anyway because there was a sizeable gap in the panels. I slid mine foreward and redrilled and sealed up the gap. Not great, but better. also, while in there, Looking up to where the cabin rectangular supply duct (black flex duct) is I noticed a roughly 2" hole just aft of the duct. If you look down into the supply register, you can see the duct opening, and right next to it a 2" hole back into the return plenum. I've removed the electrical outlet under the table so I can reach in and seal that up also.

As I said, there is likely more to be done to make the "return" actually draw through the grille, but I'm going to let that wait until next off season.

 

[DMD3]

Thank you. I will check for the sensor placement. I like what you are doing here. My primary concern is keeping the evaporator/compressor coils clean of dust and debris over time. Would be nice to see a duct of some kind between, and directly connected, to the webasto unit and return grill so only return air makes it to the unit through the grill filter. Currently there appears to be many other ways for air to find its way into the unit with it sitting free under the helm seat.

 

[Jcat2010]

unfortunately the construction of the FCF unit makes it difficult to "duct" into the coil. The FCF unit appears to be designed to be installed in a "box" plenum connected to the return register. The space under the helm could have been such a plenum, but as is, there are a lot of cables and hoses that also pass through the space, so I'm not sure how well it can be sealed. I'll update if I devise a better solution than what I'm doing now. I'll also be using some self rinsing coil cleaner next summer (it needs coil condensate to work well). It ain't perfect, but it's a huge improvement.