The smaller cord was not letting enough amps through and the resistance was eating up the cords and ultimately the power box. I replaced the power box and the cord with fantastic results. Symptoms: Cord getting hot at the plug in and at the switching box. Both AirCon’s would not run at the same time and had less capacity.
https://www.amazon.com/Conntek-14302-Generator-Power-30-Foot/dp/B00268VSJ6

