OMG, are the house batteries actually reading Ĺ volt? If they are that low, itís doubtful if the charger will recover them. The battery boost solenoid gets its plus 12 Volts from the coach battery. If the coach battery is way low, the boost will not work.
You could try disconnecting the house batteries right at the battery terminals to see if the 12 volts returns. If it does then the charger is working and at least one of the house batteries has shorted cells. Always remember when replacing battery banks to use the same brand and model and if at all possible, make sure the date code is the same.
Have Fun!! Mark & Donalda 04 Horizon 40WD no TOW 90,900+ miles and counting
Triumph Bonneville & Susuki S40 on the back