Advice for AC issue please...........

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Tom Stewart

New member
Jun 29, 2005
I have a 1993 Dutchmen Classic 30' Fifth wheel that I purchased last October to primarily be used at my quail hunting lease over the winter months in So. Texas.

The unit is in excellent condition, however the AC does not really cool down the trailer in any weather above 85 degrees...I need to get more AC. The current unit is a 13.5K BTU.Here is what I have done:

1. Had the dealer where I purchased the unit check the ac...said it was working fine but that the aluminum fins needed to be straightened with a comb.

2. Thought about putting in a second unit for the front bedroom but I only have a 30 amp service and one tech is stating that I cannot add a second unit without a serious wire project....

What other options if any do I have.

I can replace the current 13.5 with a 15 or I can add another 13.5 for the bedroom and only run one unit at a time or run a second shore power to run the bedroom unit, which might prove to be expensive.....

Me and my wife now want to use the unit for some travel since it's such a nice unit but I definitely need more ac.....

Your thoughts would be much appreciated.

Tom Stewart
Richmond, TX
I have a LOT more AC than you do and above 85 is still suffers,,, course I may have more MH than you do

Likewise the dash AC on my car don't much cut it at 90 either

There are some limits on what a good AC can do, with the banning of R-12 those limits got more severe.  I would suggest that you browse a good AC book, your local library may have one, or Pep Boys, Murray's Auto, Or other Auto "Super store" that sells auto repair books

All of these books should have a chart, the chart has a multiple demensional graph

Inside temperture (Inlet to evaporator) Outside temperture (Inlet to condenser) possibly humidity and finally outlet temperture range.  They explain the relationship to all of these.

Baisically, with the outside temp in the low to mid 70's you should see a 30 degree drop beween evaporator inlet and outlet

As the outside temnp rises... the drop drops.  however today at nearly 80 out I was seeing 33 difference between "Cabin" temp and "Outlet" on my car, in ac-max mode (Which means cabin temp is the inlet temp)

On my car, for assort reasons I monitor outlet and inlet temp all the time

Your rig is probably wired for 30 amp. service, so running 2 a/c's would require some kind of load shedding device to cycle the units. Each a/c should have at least a 15 amp. circuit depending on the unit you have or buy. Wiring could be a big project and expensive, but not impossible.

Going from a 13.5k to a 15k won't buy you much at all - that's only a 10 percent increase. Before shelling out a lot of money for new a/c's, try some things to keep the heat load down, like window tinting or reflective inserts for the windows, clean white roof, awnings, etc. It's amazing the differrence a little window and roof treatment will make. Also, where and how you park can make a big difference. While it might be nice to see the morning sunrise from your side windows, your 5'er is like a hotdog on those rotating grills at the local Seven-Eleven, getting it from all sides and top. Try 'snubbing your nose' at the sun - face the end to the East or West; not the sides and, if possible, take advantage of any shade in the area.
Chances are your Dutchman lacks dual pane glass or good insulation - that's a pretty common shortcoming in that vintage and model of trailer.  That means you are gaining heat as fast as the a/c can cool and even  two units will likely need to run full time above 85 degrees.  You can help a bit by following Karl's suggestions.  Other things you can do are to block any ceiling vents/skylights with foam pillows - Rv stores sell 14x14 pads made for the purpose, but you can buy a chunk of 2" foam in most any craft or fabric store too.  In addition to adding reflective window tint, you might consider making inside covers for some of them.  1/4 foam core poster board is easy to work with and can be cut to desired shapes - Walmarts, craft and office supply stores all carry the stuff.  Draperies that close is another option.  Anything that reduces the heat exchange will help quite a bit.    And if the roof will not clean up to a nice reflective white, it may help to paint it with Koolseal or a similar mobile home roof coat product.

Adding a second a/c basically means a second power source, either a genset or shore power. Not all Rv campsites will be wired to provide separate 30A and 15/20A outlets either.  I doubt if this wold be worth the investment - better to save your $$ towards a trade-in to a better model.

At those temps it is usually difficult to keep a coach cool. If you don't have dual pane windows you are probably gaining a lot of heat inside from that. They do make a difference. Unfortunately they are not inexpensive to install. :(

I believe the compressor on the AC requires around 17 amps when it starts. Running two on 30 amps will only work if both compressors do not start at the same time. There are some coaches with devices control units that allow the use of two AC units but it would require extensive rewiring. Even doing all of that may not help as much as you would want.

Thanks for all of your replies...It seems that maybe shedding a few pounds may be a better solution than trying to cool this unit off by ac...... ;D

Thanks Again,
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