AC Not Blowing Cold

Sounds like it's icing up...restricting the air flow. Some units have a sensor that automatically shuts off the compressor before it ices up too much. Do a Google search of your model # for proper operation.

Run the fan on high to reduce the possibility of it icing up.

also make sure the filter is clean

Is your A/C Ducted throughout the Trailer, or is it simply in the middle of the ceiling where it blows cold from there only?

I agree 100-pct with all of the above suggestions, but want to add that the Ducted ones have Frost Sensor that's meant to stop the cooling so it won't freeze over.

If there is a sensor, it could be operating normally, but it's very common for them to fall out of their designed location near the cooling coils.

If it's at all humid out, run the A/C Fan on HIGH, just like they said above.

Like others said run it on high. This kind of experience has been reported for years. We experienced it too.
We leave our in the auto position but it must have been set, in low, at the time.
After recently having the ac worked on and discovering non sealing of cold air output, and part of the cooled air returning to the warm air intake side, I wonder if that might be contributing to the problem.
Since we sealed the vents, where seals should have been, air is much colder and whole coach cooled a lot better. Haven't been in damp hot air and set iow to find out.

Thanks for the replies. this is a Ducted system. This sounds like a problem I may have to live with. However, I will look a little deeper and make sure everything is connected properly. I do think for the size of the trailer 30' the AC 13.5 is too small should have been a 15k btu unit.

My trailer is a toy hauler and only a 30amp system so adding a second AC is not a option. A upgrade to 15k may help if the one I have now ever tanks.