New to this forum. Have been looking all over for some advice on using a window AC for cooling. Long story short. I installed an 8000 BTU window AC in a Chevy 1500 express and just completed my first trip to Southern Arkansas (temps near 100 degrees) The AC cooled the van just fine but the humidity was way high (over 80 percent). When I chose the 8K BTU I was told that a 5K BTU would be too small and not do the job. It seems that the 8K is too big and not able to take out the humidity. Is there any first hand knowledge on this subject. I searched and found some information talking about the cooling of different AC's but not much information on humidity reduction. My Van is well insulated.Thanks in advanceDon Smythe

yep, you might have too big a one and it keeps shutting down. needs to be running more or less constantly to take out humidity. that is why they size them to fit houses, etc.bumpy

When I installed a roof mounted ac on a sprinter I also was given wrong info and went to large. The only cure I could find was to leave both door windows open about 4 inches so the ac could get maxairflow thru the unit. This helped but it never worked properly. Good luck

dsmythe wrote: I installed an 8000 BTU window AC in a Chevy 1500 express ... The AC cooled the van just fine but the humidity was way high (over 80 percent). Don SmytheI got a used 7K btu LG portable to deal with temps over 90 when my roof top on my van wasnt keeping up (in direct sun). It stands in the van with the exhaust hose out one of the little sliding windows. I tried to use it as often as possible in conjunction with my overhead AC (when I had adequate amperage). The water streams out of the overhead to the outside, but the LG inside is not plumbed to get rid of water so I run it without the dehumidifying function. That, and a small clamp on fan directed right at me seemed to keep me and my dogs cool enough. I did notice that just when I stopped after driving the van would really start heating up and I eventually figured I needed to open the hood to let the engine cool off. I also put up material between the drivers compartment and the rest of the van to limit the heat from the engine and the front windows. Now all I have to do is figure out how to keep my van heated since the overhead doesnt keep up with that either when temps drop below 40. I did get some insulation and will try that.

Bumpyroad wrote:yep, you might have too big a one and it keeps shutting down. needs to be running more or less constantly to take out humidity. that is why they size them to fit houses, etc.bumpyX2 - sizing A/C's is another area where bigger is not always better or more is better than less.Your A/c is probably too large for your unit and it shuts down more frequently than it should.

Sounds crazy but try running a small heater on low to give some false heat and will assist with humidity removal. Opening the window just makes matters worse.

air condition vs humidity | Good Sam Community

20 Replies

mlts22
Explorer II
Sep 13, 2013
If one has a large one, place it in the tub or shower stall and let the greywater tank go from there.

Don't mess with the little Peltier-based dehumidifiers. They are worthless, and get teaspoons of water in the time a compressor based unit gets pints out.
Bumpyroad
Explorer
Sep 13, 2013
dsmythe wrote:
I have looked into a dehumidifier but find it about as confusing as getting the right size AC. What size/model is best to get. Van is 78 sq ft and 351 cu ft

you can adjust a decent one with a humidistat so over sizing it is no problem. set it on a counter and let it drain into the sink.
bumpy
dsmythe
Explorer
Sep 13, 2013
I have looked into a dehumidifier but find it about as confusing as getting the right size AC. What size/model is best to get. Van is 78 sq ft and 351 cu ft
Airstreamer67
Explorer
Sep 13, 2013
Get a small 120VAC dehumidifier. It works magic keeping things dry and comfortable.

If your amperage is too high running both the air conditioner and dehumidifier, run a dedicated extension cord to the outside and plug into a separate outlet.

A dehumidifier also works in the wintertime when things get wet from the propane heater, stove, shower, etc.

I run mine even when I'm not camping to keep the mold away since I live in a semitropical climate along the Gulf Coast.
SkiMore
Explorer II
Sep 12, 2013
dsmythe wrote:
I'm testing now. Current outside humidity is around 75%. I have very little condensate compared to my house unit which is dripping constantly. I just tried the little heater trick again and inside humidity dropped to 45% and temp dropped to 65 degrees with thermostat setting at 72. Apparently, this is an AC that's simply too big. Problem is, I don't want to go purchase new air conditioners just trying to find one that works. That gets expensive. It would be nice to fine somebody that's been there and done that and could say exactly what size AC will work

Do you know anyone with a 5000btu window unit you can borrow?
Or buy one from a store with a good return policy and give it a try.
goreds2
Explorer
Sep 12, 2013
A BIG key is to get the van in the shade as much as possible. :)
dsmythe
Explorer
Sep 12, 2013
I'm testing now. Current outside humidity is around 75%. I have very little condensate compared to my house unit which is dripping constantly. I just tried the little heater trick again and inside humidity dropped to 45% and temp dropped to 65 degrees with thermostat setting at 72. Apparently, this is an AC that's simply too big. Problem is, I don't want to go purchase new air conditioners just trying to find one that works. That gets expensive. It would be nice to fine somebody that's been there and done that and could say exactly what size AC will work
time2roll
Nomad
Sep 12, 2013
On hottest days my home unit will run close to 100% on the upstairs. If cooling from a heat soak it has run 4+ hours continuous before cycling. Downstairs seems oversize as it will be maybe 25%.

RV 13.5 will run 100% from noon to sundown on hottest days.
KK_R
Explorer
Sep 12, 2013
smkettner wrote:
What is the compressor duty cycle? 25%, 50%?

Is there anything close to a "normal" duty cycle? (I am assuming, but not certain, that the duty cycle is the ratio of time the compressor is running to the total time the AC is running. Correct?) My 10-year old Fedders is running about a 25% duty cycle: About a minute or so on and then three minutes off. I never paid attention before, but that seems mighty short. It also doesn't seem to be cooling as fast/well as it used to. I am running it at home, when temps are in the 80s to low 90s. Humidity is typically pretty low--teens and twenties.

Time for a new house AC? Or could this be considered normal?
______________
Just to clarify for anyone following my questions: I am talking about my Roadtrek "house" (as opposed to dash) AC here--the Fedders mounted in the rear of the RT.
time2roll
Nomad
Sep 11, 2013
Does it produce any condensate? If so is it getting outside?
What is the compressor duty cycle? 25%, 50%?