The rooftop AC was having trouble starting while on ‘shore power’ and likewise when the power source was the generator. Most of the rooftop units are 1 ton non inverter type compressors running on 120 volt which has a high starting amp draw. There has been plenty of discussion on the subject on the ‘RV’ forums. I have found that the general conscientious has been that the only solution is using a microprocessor controlled device such as Micro-Air EasyStart.