I have a 2020 travel trailer with a coleman mach 15 in a 33ft travel trailer, with 2 bedrooms. In the back bedroom I have a portable a/c with the door shut, that room is no concern to me other than it would be a no go without it in the texas sun.The 15k btu coleman mach 15 only task is to cool the living quarters living kitchen etc. we keep the other bedroom door closed.When the sun is out & with a heat index of 94-95+ the best the a/c can do is about 81 degrees. At night it will freeze you out but during the heat of the day warmish air out of any of the ports including the dump vents.It doesnt' act 'froze' up either... We keep the filter clean. I was thinking either the wall t-stat is faulty or possible the freeze switch is faulty shutting off the compressor.. What are your thoughts?

Under your conditions, 81 deg. actually seems about right for a 15k. What is the temp. of the air coming out of the vents? Open the bedroom door and let the two ACs work together. Turn on the vent fan in the bathroom.

Son of Norway wrote:Under your conditions, 81 deg. actually seems about right for a 15k. What is the temp. of the air coming out of the vents? Open the bedroom door and let the two ACs work together. Turn on the vent fan in the bathroom.I don't see how that is 'normal' we get sticky skin and sweat just sitting still. A cool breeze in the shade might actually feel better

Sorry that I wasn't more clear. My coach has a 15k Coleman up front and keeping the front living area at 81 deg. is about the best it can do when the RV is sitting out in the sun with an ambient temp in the 90's. It is not enough cooling power. I have to combine it with the rear AC (which I think is 13.5k), a fan, the bathroom vent fan, and thermal curtains in order to keep the RV habitable.

Matt1221 wrote:Coleman mach 15 in a 33ft travel trailerWe had a Mach 15 in our 31' Greyhawk and it couldn't keep our coach cool when temps outside were above 95*F. If we drove thru the Southwest in the Summer, we would bake inside the coach. Temps would be 105* outside and 100* inside.Awful.Then about two years later, the whole thing cr*pped out. Died. It's like all of the coolant evaporated.I needed a replacement immediately so I replaced it with another Mach 15. It's on our to-do list to yank the Fantastic Fan out of the rear bedroom and plunk a 13.5K unit back there.For an interim solution, we've picked up a couple of 9K BTU portable AC units. I duct them out the window. Between the 15K and the portable we can make the coach habitable.

Wow this really suck then. I figured something had to be a miss somewhere. I have a 9k btu portable in the rear door sealed bedroom & it keeps it cool in there.. of course it probably less than 70 square foot tho lol. I was actually looking at a mini split, much more efficient but would take a hit on resale value & have to modify things... We are full timers and don't expect this tt to last all that long even tho it is brand new 2020 model.

Mach 15 a/c not cooling well | Good Sam Community

Son_of_Norway
Explorer
Jun 30, 2020
Under your conditions, 81 deg. actually seems about right for a 15k. What is the temp. of the air coming out of the vents? Open the bedroom door and let the two ACs work together. Turn on the vent fan in the bathroom.
Matt1221
Explorer
Jun 30, 2020
Son of Norway wrote:
Under your conditions, 81 deg. actually seems about right for a 15k. What is the temp. of the air coming out of the vents? Open the bedroom door and let the two ACs work together. Turn on the vent fan in the bathroom.

I don't see how that is 'normal' we get sticky skin and sweat just sitting still. A cool breeze in the shade might actually feel better
Son_of_Norway
Explorer
Jun 30, 2020
Sorry that I wasn't more clear. My coach has a 15k Coleman up front and keeping the front living area at 81 deg. is about the best it can do when the RV is sitting out in the sun with an ambient temp in the 90's. It is not enough cooling power. I have to combine it with the rear AC (which I think is 13.5k), a fan, the bathroom vent fan, and thermal curtains in order to keep the RV habitable.
pconroy328
Explorer
Jun 30, 2020
Matt1221 wrote:
Coleman mach 15 in a 33ft travel trailer

We had a Mach 15 in our 31' Greyhawk and it couldn't keep our coach cool when temps outside were above 95*F. If we drove thru the Southwest in the Summer, we would bake inside the coach. Temps would be 105* outside and 100* inside.

Awful.

Then about two years later, the whole thing cr*pped out. Died. It's like all of the coolant evaporated.

I needed a replacement immediately so I replaced it with another Mach 15. It's on our to-do list to yank the Fantastic Fan out of the rear bedroom and plunk a 13.5K unit back there.

For an interim solution, we've picked up a couple of 9K BTU portable AC units. I duct them out the window. Between the 15K and the portable we can make the coach habitable.
Matt1221
Explorer
Jun 30, 2020
Wow this really suck then. I figured something had to be a miss somewhere. I have a 9k btu portable in the rear door sealed bedroom & it keeps it cool in there.. of course it probably less than 70 square foot tho lol. I was actually looking at a mini split, much more efficient but would take a hit on resale value & have to modify things... We are full timers and don't expect this tt to last all that long even tho it is brand new 2020 model.
Second_Chance
Explorer II
Jun 30, 2020
Closing a bedroom door does little unless you can also close or block off the vents in there. You don't say what make and model your travel trailer is, but not all are created - or insulated - equal. IMHO, 15K is not a lot of AC for a 33 ft. TT in the conditions you are describing. We have two Coleman Mach 15Ks on our 35' fifth wheel and they keep the inside of the coach at 72 - 74 with temps in the low 90s and heat indexes in the upper 90s (plenty of humidity in the mid-Atlantic states right now). Is your RV prepped for a second AC?

Rob
sgfrye
Explorer
Jun 30, 2020
what you are experiencing is about normal if you can't get into a very shaded spot
carringb
Explorer
Jun 30, 2020
My trailer is 37' overall, and cools suitably well with a single Coleman 15k. One big upgrade I did however was slide toppers. Without these, I could feel heat radiating through the slide ceiling in hot weather.

If your A/C unit is not cycling, it's probably working as intended, and your trailer simply has a higher heat-load than mine. If it is cycling the compressor, you might have an issue.

Also, don't forget to check voltage in the trailer during peak A/C use. If voltage is low, your compressor will be pulling excess amps.
colliehauler
Explorer III
Jun 30, 2020
Lots of things you can do to improve temperatures. Put reflective insulation on the windows and keep the blinds closed, single pain windows are very poor heat/cold barriers. Park in the shade from the afternoon sun. Don't open and close the doors a lot. Use a fan for circulation of air. You do these things and it will improve temperatures. Parking in the shade is the single biggest thing you can do to improve conditions.

If you look at a tour bus you will see as many as 6 A/C units on them.

I'll disagree about opening a vent your letting cool air out and drawing warm air in.
Captain_Happy
Explorer
Jun 30, 2020
I'm living stationary in a 40 foot 5th wheel here in southern Nevada, summer temps in the 100's and higher. since I don't move this unit I installed a real small evap cooler to maintain the temps in the main living area during the day. Because the larger 15 BTU A/C just doesn'0t cut it. Full sun during day, thermo pane windows help alot. so far it's maintained temps in the high 70's & low 80's durung the day time. At night I run my 13.5 up in the bed room, which will freeze you out. Now I know this setup will not work if your traveling around.

There is also some people on the forums that have installed 12 BTU mini-spilt units to there units rigs.