2017 3661RL
HOPE SOMEONE FINDS THIS USEFUL - AS FOR ME...MY NEXT STEP IS TO SELL IT.
There is a lot of information regarding issues with the Dometic ducted AC systems on the site. In my case I have two Dometic CT capacitive touch thermostats, controlling a Blizzard NXT 15k in the rear and a Penguin 15K in the front. I like many others have been plagued by the issues, and there appears to be no “exact” fix. Dometic and Keystone seemingly have completely looked away from what appears to be an ongoing problem since about 2015 based on my research.
Contact Dometic and they love to respond by sending you new thermostats or the faceplates. I guess they have had good results lulling folks into believing the issue is fixed by pacifying them with some response at least.
Folks describe the same issues over and over. (Not just Keystone Customers)
Thermostat issues: Temperature Accuracy. Touch controls seeming change on their own or with a simple brush of clothing.
AC Unit Issues: Units don’t run correctly on anything other than HIGH FAN (Maybe). Units shut off sporadically for no reason at all and will not restart without a reset. Units cycle, run for a few seconds shut off, then restart over and over.
I’m sure there are other scenarios and more than likely the few that I described I didn’t get completely right.
The bottom line – THIS STUFF DOESN’T WORK THE WAY IT SHOULD. No end in sight, no matter how much troubleshooting you or your preferred RV repair service does.
In my particular situation I am out of warranty as I am the second owner of the trailer, and based on what some others have gone through getting the issue looked at, I am not willing to pay the labor rates for the many hours of investigation. So…I either live with what I have and attempt to improve my scenario or eat the cost of some other AC solution and trash what is there. IM CHEAP!!
At this point I made the choice to IMPROVE my current system as best that I can in the hopes of alleviating/eliminating the problems.
Nothing that I list below hasn’t been discussed previously on the site. I just wanted to put it all together in a list for folks.
1. Thermostats – If you are having issues where your thermostats have a mind of their own. Reach out to Dometic support and obtain new faceplates. If you continue to have issues keep communicating with them until another set of faceplates, or complete thermostat replacements alleviate the “mind of their own” issue. Believe me they love to send these things out. Examples of this are where the thermostats change settings on their own.
Insulate the cavity behind the thermostat – I found that the heat in the wall was causing severe problems with temperature accuracy. I was able to use a combination of rolled insulation and spray foam to provide enough surface area behind the thermostats that allowed them to pick up the ambient temperature in the room vs. fight with the heat in hollow wall cavity.
While you have the thermostat off the wall. Check the wiring job. Clean it up. Even though mine were wired appropriately I found one thermostat to have wire exposure in the insulation further down the wires from the terminals.
2. Duct Work – Specifically check for collapsed duct work for your WARM air returns. All of my warm air returns were collapsed. I used two 9” pieces of 1.25” PVC on either side of each duct to open them up. Right off the bat there was a significant increase in the performance of the system. I checked my cold air supply duct work and found all to be OK. A bore scope helps.
Check all cut openings in the duct system – Both warm and cold air ducts at their cut opening points need re-tapped ensuring a positive seal. INTERIOR: For the cold air diffusers inside the 5ver this will ensure that cold air being pushed from the AC units flows fully into the trailer and not between the duct and the ceiling panels. For the warm air returns it will ensure that supply air back to the AC is pulled from the 5ver interior and not the cavity between the roof and the ceiling. Almost all interior cut openings in my case had to be re-tapped so I redid them all. The foil tape was either junk to start with or deteriorated enough over two years that all openings separated. EXTERIOR: Yep there are cuts on the roof to check. Get up on the roof and pull the covers off your AC units. Remove the plenums and you will see one hole for your warm air returns and the other hole will be for the cold air supply. You should see where the same tape was used to seal both openings to their respective ducts. In my case there were huge gaps where the openings, both front and rear locations, had separated. Once again allowing cold air into the roof/ceiling cavity and warm air to be pulled from the cavity. NOTE: Bring a vacuum to get all the wood chips from the factory picked up.
3. AC Unit Mount Position – While you’re on the roof pay attention to the positioning of each AC units with respect to the openings cut at the factory. I had to reposition my front AC unit 2” forward as it was out of alignment with the holes that were cut. Essentially allowing the recirculating of cold air leaving the system right back into the warm air return. NOTE: At a minimum make sure the AC mounting gasket is present in between each of the holes cut in the roof.
4. Cold Air Diffusers – Two things here. First trim the base/collar that inserts into the ceiling to ensure it doesn’t protrude into the duct restricting air flow. Second, optional, remove every other vent blade to allow increased air flow exiting the duct. Or just buy new diffusers that have a shorter collar length and are more open to better air flow. I’m CHEAP. If you take your time removing the blades/fins it looks good and works great.
5. Vented Steps – My steps are vented directly to the basement. Not sure if all 5vers are like this or not. I removed my basement wall to expose the back side of the steps. I was able to fashion a piece of black vinyl sheeting so that would act as a damper to block warm air being actively drawn into the living space.
In the end. I feel I am light years ahead of where I was at. I am not willing to say that all is fixed at this point but time will tell. However, my unit has been hooked up next to my barn for the last three weeks. Temps here in Ohio have been in mid 80s to 90 and humid with a few cooler days. Both TStats have been set at 75 and on AUTO. So far no issues. No shutdowns. No cycling. Knock on wood. You watch I’ll check everything tomorrow to find it off line. Even if that is the case. The system, when it runs, runs effectively now and doesn’t struggle like it used to.
If anyone has any questions. Please feel free to reach out.
Thank you to all the previous posters for their informative posts that allowed me to step thru all of this.
Use caution on the roof and make sure all systems are shut off prior to any work being conducted.
Gordo
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