There is typically no filter capacitor on those. It just outputs raw rectified DC, so it would be normal to see both AC and DC on a meter. I am surprised that the output voltage reads that high. There are typically two types of outputs on RV power converters. One is for charging the battery and one for directly running the accessories in the motorhome. The accessories output should read around 14-16V with a small load on it like a typical 12watt RV light. The charger output could be acting strange because it isn't connected to a battery yet. What type of meter are you using to measure it?