If you have a leak, then the odds are ALL the coolant has leaked out and it would no cool at all. They only hold 1 lb of coolant and most leaks would allow that small amount to completely be gone. You need ALL parameters checked
1. Evaporator cleaned
2. Condensor cleaned
3. air filter/s cleaned
4. Once that is done you need a AMP draw test based on ambient to determine the state of charge and the condition of the compressor. This is the ONLY way to determine the state of charge on a RV AC unit. Doug