If your ABS light is on, the first thing I would do is to crawl underneath and clean the 4 sensors. You tube is your friend here.
Re the rooftop AC units, I would look into a "Soft Start" module, usually advertised on the right side of the forums. They work !!!
The dash air needs some juice ? That you can DIY.
Mike in Colorado
2004 Fleetwood Pace Arrow 37c,(Jezebel) Ultra RV ECM / TCM and rear track bar, PPE deep Tx pan, Bilstein's, Sailun's & Sumo's all round, pushed by a 2014 Chrysler T&C, on a Master Tow Dolly.