You can buy any brand capacitor and it will work with whatever motor you are using, you just need to match the MFD rating on the replacement with the factory capacity.
You can buy a replacement fan motor, compressor, and perhaps other parts. Circuit boards should be around for a few years. Look at your local TransCold or truck air refrigerator supply house for the parts for your A/C. Carrier is still making mobile air conditioners and refrigerators, just not finding the RV market as profitable as the trucking industry.
Good luck,
Fred.