I’m having a problem with one of my 2004 parallel stacked SW4048’s. It started dropping AC1 and switching to inverting on a regular basis (about every 10 minutes during the day, never at night or early morning) and switch back in within 5 minutes. Grid power has checked out ok and all my large loads are good. Once in a great while (maybe once every 1 or 2 months) the inverter/ charger circuit breaker trips on this same inverter. I recently disconnected the solar panels from the system and the problem inverter held until I reconnected them and it went back to acting up. Also, the cooling fan is not coming on in this inverter, is overheating causing the switching problem? Is it usually the fan motor or switch at this age and is it repairable? Your thoughts please?...thanks very much, Vic.