They are SEALED(soldered) systems and have no ports for adding Freon. They have no ports or areas for Freon to leak out unless they have a cracked line. The maintenance is to keep the Evap and Condensor coils clean and the Air filter clean. Doug
I'm sure the experts will pop in but the air units don't need freon unless they are leaking. We did have our front roof unit replaced under warranty as it bit the dust. The other two units work great and are very cold in 5 yrs of ownership.
You should check the roof units once a year to clean the 'fins' and to check for critter infestation.
2008 Monaco Dynasty, 42.2 ft., 4 slides, 425 hp clean-air Cummins diesel
2013 Honda CR-V EXL, AWD, w/Nav, SMI Air Force One vacuum-assisted braking
Other than keeping the coils and filters clean there isn't much you can do to them.
There are two sets of coils. One is on the back of the AC and the other is behind a sheet metal plenum. This is the cooling (evaporator coil) and inside air is circulated through it. Dust and pet hair can clog it and reduce efficiency and if bad enough can cause freeze up after running a few minutes.
Clay (WA5NMR), Lee (Wife), Katie & Kelli (cats).
Now snowbirds after eleven years Full Timing in a 2004 Winnebago Sightseer 35N, Workhorse chassis, Honda Accord toad
I have a good friend who's business is repairing commercial refer units on trucks & trailers. He helped me with a Coleman unit that went bad many years ago and this is what I learned... the units are "sealed" and do not have service ports installed. There are clamp on devices that pierce the tubing to allow for testing and charging. I was told they are really only a temporary solution. Turned out the compressor was bad most likely from never getting used.
2009 Komfort 256TS
2001 Dodge Ram 3500 QC 4x4 Cummins DRW
2005 Dodge Durango Limited AWD HEMI
2001 Sebring Convertible
1995 Miata M-Edition
1 Wife 2 Boys UW & Bellevue College
1 Trixie (Bichon Frise)
Only 23 years to retirement!!!!