RV air conditioners should not normally require recharging, but the cooling fins should be cleaned out regularly. Dirty cooling fins are a common cause of poor performance.
The following video from RVTravel.com explains the process clearly. The unit on my motorhome is a little different, but the cleaning process is the same.
...and here's a fairly good article at rvtrax.com .
You will need a compressor, brushes, a vacuum, rags, a pail of water and a cleaner/degreaser.
When the cleaning is all done using the process described in the video, you can test the efficiency of the system using two thermometers. There should be a temperature difference between the inlet and outlet air of 20 degrees Fahrenheit or 6.7 degrees Celsius. If the difference is significantly less than that, you will want to take your AC to a professional.
Here are some photos and notes from the cleaning I did this week.
|Metal Shroud, and plastic shroud in the background|
My unit has two shrouds, with a metal one nested beneath the plastic one (Above and below)
|Side mounted screws|
|Dusty cooling fins|
|More dusty cooling fins|
In the next picture the unit is all cleaned and being reassembled.