Forum Discussion

bsbeedub's avatar
bsbeedub
Explorer
Jul 22, 2022

AC air not cold

I used to have a 23 foot travel trailer with no slides so it was small. The AC could keep it cool no matter the outside temperature. The air blowing from the AC was always VERY cold. The AC was a Coleman Mach with 13,500 BTUs. It was the style with no thermostat and ran constantly but the compressor cycled on and off.

My one year old 30 foot 5er with one 12 foot slide can’t come close to keeping it cool even when it was brand new. First thing in the morning the air is not near as cold as the old TT so it struggles right out of the gate. We’ve been gone for three hours with all of the shades closed and it can’t maintain temperature. This AC is 15,000 BTUs but is a Coleman Mach with a thermostat.

Is the AC just a lemon or is there something I can do to make the air colder?
I’m not talking air flow, I’m talking temperature of the cold (cool) air.

I was in a park last year and the guy across the road was having AC issues and his unit was not blowing cold at all. He called a mobile RV tech and someone came out and either topped it off or recharged it completely. The owner said it was then running like new. I’ve always read (here, as well as other sites) that these systems are closed and can’t be topped off or recharged. Apparently, that’s not the case. I may have to resort to calling a tech to see what they have to say.
Seeking Advice
  • smthbros's avatar
    smthbros
    Explorer
    Jul 23, 2022
    The problem with the "20° rule" is that it accounts for only the sensible heat load while ignoring the latent heat load. I wonder how many air conditioners have been replaced due to failing to achieve 20° temp drop? I suspect the air conditioner salesmen and manufacturers do not mind.
  • prichardson's avatar
    prichardson
    Explorer
    Jul 23, 2022
    Take temperature readings at the A/C air return and the closest register (or better at the quick cool register if it has one) if the difference is 15 to 20 degrees it is doing what it should. RVs are notorious for having thin insulation and poor sealing of the duct work so if the above is correct you could be losing cooling ability there.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jul 22, 2022
    There are a few things. As someone said it might need a re-charge.

    But it might just need a condenser cleaning. You said COLEMAN right.. These are easy Here's is how

    Up on the roof (Isn't there a song by that name?) You need a #2 or 3 Phillips head screwdriver Remove 4 Bolts from top of A/C Cowl and lift off Cowl.

    now peal the crud (you might need a soft brush) off the condenser.

    See if it now works better (Replace cowl)

    Cowl also called Shroud.

    Other makes
    Remove about a dozen screws around base of cowl and lift it off
    Figure out how to open condenser compartment (May be a few more screws or it might be cut tape and bend tabs (Stupid design)

    You may (If you have XXL hands) need to remove fan and to do this you may need to dismount the blower motor (Gets to be more and more fun)

    Then you clean off the dang thing (Vacuum cleaner may help)

    Re-assemble and test.
  • MFL's avatar
    MFL
    Nomad II
    Jul 22, 2022
    My Dometic 15K AC does a great job, cooling my 31" FW. I also think it has more to do with the insulation and build quality, rather than an AC not doing the job. My FW is described as 4 season, and is the most quiet inside of the 4 I have owned. Does your coach seem stick house quiet, when camped in a RV park, or does it sound like the door and a window or two are open? That describes my previous FW! :)

    I can start mine any time, even when temps are high inside, and it catches up, slows to low fan as temp gets near stat set temp. It then cycles on/off when set on auto, but never needs to return to high fan to keep up.

    Jerry
  • bsbeedub's avatar
    bsbeedub
    Explorer
    Jul 22, 2022
    Durb wrote:
    I have a 31 ft' fifth wheel. The air conditioner was installed incorrectly at the factory. They left the divider off that separated the input and output air so it just churned and didn't cool. Made a makeshift divider and fixed that problem so now the air conditioner works fine. You might want to remove the inner panel to make sure you have good separation with no lair leaks between chambers.

    Our trailer has a bunch of windows. If is going to be hot, we have to start the air when it is still cool outside to give it a fighting chance, blinds down. Involves some sweater time in the morning.

    We're in the northwest so it always cools down at night and we never sleep with the air on. You might want to disregard this if it stays hot all the time where you are.

    We also had a Bigfoot trailer with a 22 ft. box, dual pane windows and very good insulation. I figured one could make ice cubes on the counter with the air conditioning in there if they wanted to.


    I’ve read different things and watched videos of how to make your AC blow colder air and many of them talk about and show the divider you’re referring to. I opened mine up hoping it was going to be that simple. It had the divider in the correct place so I was back to the drawing board. I used the silver HVAC tape to try to close some possible leaks and nothing changed.

    Thanks for the suggestion though.
  • wanderingaimles's avatar
    wanderingaimles
    Explorer
    Jul 22, 2022
    CA Traveler wrote:
    If the outlet air is 20F cooler than the input air then the A/C is working as expected and you have inadequate insulation or cooling capacity or both.


    This is it.
  • Durb's avatar
    Durb
    Explorer
    Jul 22, 2022
    I have a 31 ft' fifth wheel. The air conditioner was installed incorrectly at the factory. They left the divider off that separated the input and output air so it just churned and didn't cool. Made a makeshift divider and fixed that problem so now the air conditioner works fine. You might want to remove the inner panel to make sure you have good separation with no lair leaks between chambers.

    Our trailer has a bunch of windows. If is going to be hot, we have to start the air when it is still cool outside to give it a fighting chance, blinds down. Involves some sweater time in the morning.

    We're in the northwest so it always cools down at night and we never sleep with the air on. You might want to disregard this if it stays hot all the time where you are.

    We also had a Bigfoot trailer with a 22 ft. box, dual pane windows and very good insulation. I figured one could make ice cubes on the counter with the air conditioning in there if they wanted to.
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Jul 22, 2022
    If the outlet air is 20F cooler than the input air then the A/C is working as expected and you have inadequate insulation or cooling capacity or both.

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