AQV24NSBNXSA Samsung split system stops working and flashes green and red light. Repair technician replaced fan motor as it had seized. System worked for 20 mins then shut off again and flashed green and red lights. Repair tech replaced circuit board in out door unit. System worked for about an hour then shut off again and flashed green and red lights. What else could be causing this??? I don't want to have to replace much more. Why can't the techs do proper diagnostics? Steve