I help my father out part time in the summer months in his small but successful hvac business out here in the country towns around Brenham,Tx. My question is that since we've replaced a Tempstar 3.5 ton package unit in a trailer house it has started to freeze up. There are no restictions on the duct work underneath, the fan speed has been set on high, the pressures are about 90 suction and 290 liquid around 2 pm and it's reaching around 102 degrees outside. I know it's probably something simple but if I could get some advice I would appreciate it. He thinks it's a bad expansion valve but I sure would hate to have to move a 300 pound unit to replace it if thats not the problem. Please help. Thank you.