Dick,
Assuming your system is same as mine, an SCS unit, it is 27000 BTU. It has 2 compressors. The 2nd one kicks in if the primary one can't handle the cooling load. Mine cools our 41.5' coach with no problem. It is quieter than roof mounted units. The major fail mode on these units was a hole in one of the freon lines due to vibration. Fix, as I understand it, was to replace the fixed line with a flexible one. Sounds like that might have already been done to yours.
There is a lot on the forum on these so you can learn more there. A number of folks have replaced them with roof units or a Coleman basement unit. Mine has been working fine. Only problems have been with the control board, accessible in the bay just rear of the AC intake/exhausts. One failure caused the # 2 compressor to not turn on. The replacement board failed shortly afterward (warranty) and wouldn't allow the unit to turn off (woke up to a 55 degree coach).
Parts are available. Newell RVs used these for a number of years and has a repair depot for them. The control boards can be repaired for <$100 by Flight Systems so if you get a replacement, send the failed one to them for a spare. Maintenance-wise, be sure to check / replace the filter(s). They are located behind a panel on the basement wall near in the rear-most storage area (on mine).
Gerald know a lot more than I do on this so he may have some input also.
Steve