Your Xantrex may be bad but before replacing it consider plugging into a 30A shore power supply. The Freedom 458 2000 requires 21amp AC input to achieve max charge mode per the owners manual. Since your rig is 14 years old, it may even require a bit more due to aged connections etc. I don't think your current 20 amp AC input is sufficient, especially if you have anything else on.
Good Luck, Steve