Keystone "Quiet Cool" Issue

[jrp]

Whether you need 1, 2 or 3 AC units depends on the size of your rig, the max temps you use it in, and your personal comfort level.
Is it reasonable to expect 1 RV type AC unit to cool your 38 ft RV in any temps above 85? I think not.
Is it reasonable for the Mfg who sells the exact same RV nationwide for use in temps from 0 to 100, to offer the additional cooling & heating units that only some of their customers will require, as an option? I think yes.
if something is broken, duct crushed or installed incorrectly, you have a right to have it fixed. But if your only problem is you refuse to pay for the 2nd AC option, then you have no complaint in my opinion. Whether you paid $70K or $100k has nothing to do with which options you should have selected to make the rig fit your temps & preferences.

Originally Posted by mikie1

A second A/C unit would be nice. But it would cost 1200 to 1500. My
feelings again are that when you pay this much for the origional unit
shouldn,t you expect to be relitively comfortble. Is it unreasonable to
expect a 15 - 20 % decrease in temp from the outside air.

[red71roadrunner]

Last August we purchased a 2013 Montana 3100rl and experienced the same problem. Three trips back to two different dealers and it's still not fixed. After contacting Dometic and hearing from them how the A/C should preform contacted Keystone directly. I had also scoped the air intake lines (what a mess)
and collected a sandwich bag full of debris. Keystone set up the next app. with my dealer (who said there was no problem) and convinced them there was a problem. Long story short, collapsed return lines, door side line 90percent obstructed with wires, plenum full of sawdust and construction debris, A/C unit packed full of debris, three air out lines disconnected (Must have had a little problem with quality control that day). A/C had to be removed and serviced and other repairs made.
And when we picked the unit up the service manager told us they checked their lot and found 7 trailers with the exact same problem, all were in the process of being repaired.
On the plus side Keystone Had our backs and were a pleasure to deal with.
We love the trailer..

[leyland02]

Just picked up my 2013 3402RL last week and I told my wife that the rear ac wasn't blowing as hard as the front ac. My duct work was crushed in and there was a lot of saw dust in the duct work. Dealer is 5 hour away so I figured I would look into repair myself. I removed top shroud and removed the small sheet metal that covers the return air duct. Vacuumed out saw dust and moved wires that was blocking 50% of return. Then installed two screws in the matal transition piece that had dropped down help block return air. This helped out a lot. I did then could see plenty of light in duct work indicating it was opened up. Air flow is much better. I would think a $60,000 unit would not have these type issues but you can never tell. Plan on a two week trip next week so I will take plenty of tools. Someone on here mentioned inserting a pvc pipe to hold duct work open. I like this idea, as it will not restrict flow.

[wva3185]

Originally Posted by Bob Landry

It looks like a poor installation and the duct wasn't properly taped when it was installed. These trailers all use rigid duct, not flexible.

"Rigid" as in metal or "rigid" as in fiberglass. Just when I was finishing up my shorted lived career in HVAC the fiberglass duct work was just coming out. Staples, tape and fiberglass is supposed to be the equivalent of the old style wrapped metal duct work. It may be on paper but it never was in real world use as far as I could see. Me thinks if I had this issue I would want a metal liner shoved through the duct to hold it open. YMMV

[red71roadrunner]

The return air ducting in our Montana is made out of thin walled foam rubber material. I believe it was originally designed for flat ceiling application. When it is used for the vaulted ceilings, as one end is pulled down it collapses in the middle. Also with keystone approval our dealer used 2" flex hose like you would find on a spa to keep the duct open, seems to work.

Everyone should check their A/C units for debris. On top of the one cup sample I took in to show plus several cups I vacuumed out, the dealer collected an additional gallon baggie of stuff from the A/C unit and sent it to keystone.

[Bob Landry]

The lack of quality of Keystone's air conditioner installations is legendary. That said, only two things will cause icing. One is low refrigerant charge. That does happen occasionally, but given that these are closed systems that are charged through a process stub and then soldered, the likelihood of that being the issue is remote. Charge can be verified by a simple check with a clamp-on meter. Most folks do not have one, but believe me, the number of these units that leave the factory improperly charged is extremely few.
The second, and the usual cause of icing in RVs, is air restrictions caused by improper duct installation. A lot of issues can be fixed by inspecting and re-tapeing the plenum box and the ductwork around the discharge air registers. Air being blown into the ceiling isn't going to do you much good.
I said two things, but there is actually another. That would be a return air plenum that is sloppily taped and is allowing cold supply air to be fed directly back to the evaporator. Again, this goes back to sloppy installation practices.

I see this a lot on this and other forums, so I'll comment on it. Outside air temperature has nothing to do with evaluating the efficiency or performance of an air conditioner. Because trailers are so poorly insulated, it will give you a feel for how much heat is being radiated into the trailer and that heat has to be dealt with by the unit, but as a measurement, it really gives very little useful information other than affecting the current draw of the compressor. The 20 degree split is often mentioned and often misunderstood. That is a split between the temperature of the supply and return air being drawn through the coil. A 20 degree split tells you that the system is operating at top efficiency. You do have to make sure that your ductwork is good and that there are no air restrictions(or leaks) or this measurement means nothing. IF you know that the system is properly charged, and IF you know the ductwork is properly installed and you do not read a 20 degree delta T, then the unit is undersized for the size space you are trying to cool, and there is no fix for that except to add more BTUs of cooling. If you do get a 20 degree split, that's as good as it gets, you can't tweak it.