Battery won't charge

You may save time by having converter/charger and house batteries plus house battery disconnect switches and solenoid relay checked by a trusted RV service. It would be good to get a cheap digital multi-meter and learn how to check house battery voltage with and without shore power connected. The converter charger operates on 110vac power to charge the house battery when RV is connected to shore power. The house battery disconnect switch operates a solenoid switch that connect/disconnects your house battery to/from the converter charger. It must be set to "on" for battery to be charged by the converter/charger. If house battery is near dead ( 12.2 volts) the disconnect switch may not operate the solenoid relay and converter/charger may not charge the battery. Have the RV service explain how test and maintain your house batteries, keeping connections clean, and keeping electrolyte levels up adding distilled water as needed. It is likely that you need new house batter(s)if converter charger is working.