Often customers call-in requesting AC service because the unit is running but not cooling and assume that like your vehicle these units can simply be re-charged with refrigerant. Camper air conditioning units are closed systems and have no refill point. If an Open Road RV Repair technician or any RVIA Certified Technician tests your system and determines that the issue is low refrigerant charge the only option is replacement of the rooftop assembly. Note: This diagnostic procedure cannot be professionally completed by visual inspection. If your service professional does not take a temperature reading and use a millimeter to test the unit ask what diagnostic procedure they used to determine that your unit is faulty? The technician should then check to make sure that your control board and thermostat will be compatible with the new unit, if not then all of the proper installation equipment will be quoted.
You maybe told or read online that you can purchase a self installed valve and recharge your system. These saddle valves clamp over a line in your system and pierce the copper tubing allowing for a fill point. However, this 100% will void any manufacturers warranty, compromise the system possibly introducing a new leak and most notably does not address the root cause of the failure.
Service and inspect your AC annually and rely on the advice of a reputable service company, like Open Road RV Repair, employing RVIA certified technicians. In the end this is the best way to save time and money. Not to mention enjoy worry free air-conditioned camping.