Mach 15 a/c not cooling well

[Matt1221]

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?

[CavemanCharlie]

parcany wrote:
On our Jayco 33 RLDS we had only had 1 15 thousand Btu A/c. I took all the vents out of the ceiling and wrapped tape around the cone part then put the vents back in. Also on the very farthest vents away from the a/c while the vents were out I took some styraphone and blocked the duct past the vent. So when the a/c is on the cold air does not go past the farthest vent and comes out. Made a big differance in the way the a/c works. Also installed digital thermostats. In 105 temps kept the trailer 75 degrees. nice and cool Did the same mods to our Jayco Bungalow and the new Jayfeather. Made one big difference.

Good information to know.

[parcany]

On our Jayco 33 RLDS we had only had 1 15 thousand Btu A/c. I took all the vents out of the ceiling and wrapped tape around the cone part then put the vents back in. Also on the very farthest vents away from the a/c while the vents were out I took some styraphone and blocked the duct past the vent. So when the a/c is on the cold air does not go past the farthest vent and comes out. Made a big differance in the way the a/c works. Also installed digital thermostats. In 105 temps kept the trailer 75 degrees. nice and cool Did the same mods to our Jayco Bungalow and the new Jayfeather. Made one big difference.

[Gulfcoast]

I predict it's the trailer and not the A/C. I've had many trailers and they all were hot in the summer.

[Matt1221]

I've got a a/c guy coming out next week to check everything over. If this is normal it's not right. by 1030am is is pushing 80 degrees in the trailer today it got up to 88 with the outside heat index of 106 the actual air temperature was 98.
The actual vent temperature is around 73 degrees.

[ktmrfs]

we have a 33ft double slide trailer with a MachIII 13.5K BTU AC. really should have two AC units. As it came from the factory cooling was definitely sub optimal. However with a few fixes it now will keep the trailer in the mid 70's with outside temps in the 90's as long as the AC comes on when temps inside hit 72/74. No way it will cool down the trailer with those outside temps.

My mods:
1) took off the inside AC cover and closed up all the leaks in air gaps with metal tape.
2) removed all the ducted vent outlets and again, sealed up the gaps with metal tape.
3) they put a minimal number of air vents, but typically run the plenum to the end of the trailer. So, I added a second vent in the bedroom, a vent to the bathroom on the same run, and 3 more on the living area plenum.
4) replaced all the factory celing vents with an areo vent which is much easier to adjust and blows the air horizontally in a circle rather than straight down.

All these changes made a huge improvement. Still is marginal but as long as the AC comes on at 72-74 it will keep the temps in that range with daytime highs in the mid 90's. Now we are in western oregon so we don't get high temps till afternoon. If I was somewhere that had temps in the 90's by mid morning, not sure it could keep up.

[Lantley]

I would opt for a 2nd A/C over the toppers. Especially if you are full time.
As others have mentioned 1 A/C is just not enough.

[Matt1221]

It is not the most expensive model out there but it is a keystone hideout 338lhs 2 slides. A rear slide in a separate bunkhouse bedroom, and a living kitchen slide. It is wired for a second a/c but our budget won't allow at this time.

[Matt1221]

Well thanks everyone this is what I was afraid of. I feel it should be able to cool off a relatively small area, but the vent temp is too high. I guess the a/c being on the roof in direct sunlight is bad.. Unfortunately we are full timers with little say on shade & the future move isn't looking any better either.. Looks like we will check out the slide toppers to see, what they can offer. Thanks

[Hannibal]

We’ve camped without shade mid summer a couple of times over the years. We were sweating inside the TT and 5th wheel until the sun went out of sight. I don’t know if two a/c’s would have made enough of a difference. We won’t do that again.

[rhagfo]

carringb wrote:
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.

X2 to slide toppers! Makes a Big difference in heat transfer through the slide roof.

[CavemanCharlie]

colliehauler wrote:
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.

This is good advice. You might also try cleaning your inside filter and getting on the roof, remove the housing, and use a air compressor to blow out the condenser.

Colman Mach Air conditioners are sucky. Poor design.

[colliehauler]

Captain_Happy wrote:
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.

Big difference in the low humidity of Nevada where evaporative coolers work well and the high humidity of Texas where they don't work well.

[Captain_Happy]

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.

[colliehauler]

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.