Trailer: 2015 Scamp (16 Std Layout 4) with '15 Toyota Sienna LE Tug
Look for a plastic screen-like rectangular thing on the air intake, from the corners pry it out, remove the filter (its similar or the same as this), wash it, reassemble.
If you have use the A/C much it will likely be obvious what to clean.
Every so often, somewhere between 2 or 3 and 10 years, I would use A/C coil cleaner on the coil on the outside part under the shroud. The cleaner is available at many home improvement stores in spray cans.