I know that you say you have excellent voltage at the outlet but I'll bet that if you checked at your RV electrical panel, when the AC's are trying to start, the voltage will be dangerously low. Checking voltage without a load is not giving you accurate information. As an example....if all of the wires in your RV power cord are frayed, except ONE strand, your voltage will still read at 120 volts. Once you try to draw a large load, like AC units, that single, or several, strands cannot handle the current draw and your voltage inside will drop to probably close to 100 volts. This can be loose or frayed wires starting at the plug, and moving back to where they connect to your RV electrical panel. Obviously you want to be careful when working around the electrical panel, especially if you are not sure of what you are doing.