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Markpec's avatar
Markpec
Explorer
Aug 05, 2014

2013 Montana Big Sky AC concern Model 3750FL

I have a question on the ac unit in our Montana Big Sky

Our bedroom AC is a 15000 BTU AC and it works fine with no complaints. Our kitchen AC is 13500 BTU and it serves the front of the unit also (Living room) It doesn't seem to blow out the air in the front ducts like it does in the rear, making it extremely uncomfortable in the front of the unit. It is so hot in the front we can't sit there in during the day time hours. At night it gets uncomfortable at times when we don't have fans blowing. The dealer says the AC unit is working fine, but they don't sit in the unit to feel what I feel during the day time. When they test it, it is parked under roof and the AC cools fine.

I am questioning the fact that our unit is advertised to have an attic. (3-4 inches of space between ceiling and roof) Well I noticed there is no duct lines in the front. AC is being blown into the ATTIC and it supposedly forced out the holes in the ceiling they call vents It lacks duct work in the attic to direct air. the holes in the rear are closer to AC thus being forced out first in my opinion.

I'm no AC guy or a rocket scientist, but to me that is like blowing the AC in your home attic and cutting hole in your ceiling of each room hoping it will direct air evenly in your home.

Can any one tell me if this is the way it is done in these units with so called Attics? If it isn't it would explain why we can't breath some days in our front with the AC blasting in the center and in the rear.

We have been back and forth with Keystone and our dealer no one is helping solve this problem. its still under warranty.

If any one has a 2013 Montana can you check to see if you have duct lines in your vents. it would not surprise me they forgot to put all the pieces together when they made our unit. These dealers and manufacturers have attitude many times.

When we purchased our coach, we were looking at two Montana's and the other one was noticeably cooler but I didn't check the vents to see if they had ducts. As a matter of fact the sales guys said he would have the techs look into that. we thought nothing more of it and decided to buy that one since we liked its layout more

Any help is appreciated.
  • why not just call the people who manufactured it? I cannot believe there is not supposed to be duct work, have had 4 5th wheels and they were all ducted.
  • Reading the OP post was sort of confusing. If it is ducted, the ducts may be made from a fiber board or insulation board. The ceiling may be part of the system and the vents may be just attached to the ceiling.

    How about some photos of your concerns.

    Ken
  • There are ducts in the ceiling. Each A/C unit should be connected to the common duct system. Many run the bedroom A/C to cool the front without the noise and then shift to the front A/C to cool the bedroom at night (once again without the noise). Join the Montana Owners Club at www.montanaowners.com where there are a bunch of 3750 owners. More information than you ever wanted to know about your Montana is there.
  • We do not have a Montana but our front 15k a/c unit is not ducted. There is not enough room in the ceiling in our line (HitchHiker Discover America) for ducting for the front a/c. The main a/c is ducted into the bedroom. We rarely use our bedroom a/c because it will freeze you out. But then we have a very well insulated RV and have no issues in the cold or heat.
  • bob34787 wrote:
    why not just call the people who manufactured it? I cannot believe there is not supposed to be duct work, have had 4 5th wheels and they were all ducted.


    I did many times...... I have tried to get a resolution from them. Their final answer to me as quoted

    "....your unit is built as designed."

    they can't Or I should say WON'T do anything. If the dealer doesn't recommend, then they will not. On this I need to investigate to see if it is suppose to have Ducts, because the dealer just says its working fine.

    My problem was I bought it outright and then I'm forgotten until I want to buy another.
  • TXiceman wrote:
    Reading the OP post was sort of confusing. If it is ducted, the ducts may be made from a fiber board or insulation board. The ceiling may be part of the system and the vents may be just attached to the ceiling.

    How about some photos of your concerns.

    Ken


    Sorry to confuse. What I mean by ducts is small lines of tubing similar to a dryer exhaust line leading from AC to each ceiling vent.

    So what you are saying is that the entire "Attic" (as they describe) is one big Duct box ?

    If so, then that is the possible reason why our front ceiling vents are not blowing out as much air, the back ones are blowing out alot. its then unbalanced. Air will be forced out in order of least resistance and shortest distance. Since the back vents are closer to AC units it will blow out first. That is obvious by the results we are getting. Its freezing in the back and way to hot in the front. The one Montana was not like that.

    Is there such a thing as vents that close in a 5th wheel maybe we can close the back vents and force more out the front. the vents we have will not open or close. We would have to tape each vent we want closed.

    Sorry I am new and I will need to learn how to post pictures then I will

    I have a link to Video if that helps but doesn't show ducts http://youtu.be/TKXu8yYzn1A

    https://www.youtube.com/watch?v=TKXu8yYzn1A&feature=youtu.be
  • it is very common for the duct work on trailers to be very poorly done. You can 1) take it to a dealer who is working for YOU, not the manufacturer or the selling dealer or 2) do it yourself.

    If you do it yourself, easiest way is to buy a waterproof USB camera, 20 ft cord, on ebay, less than $25 delivered to your door. Load the software, plug in the camera and use the camera to snake thru the a/c ducts. I'm pretty sure you will find that much of the air is escaping into the space above your ceiling and the roof of the trailer. You can insert the camera at each vent point and check both directions, all the way to the end of the duct run - make sure ends are blocked, not dumping into the under-roof area.

    Also, it is very common for the a/c grill to allow conditioned air to feed back into the intake air, severely limiting the cooling for your unit. Do a search and find pictures of RV a/c units where the ceiling unit is removed and the area between return and conditioned air is blocked from short circuiting.