I have a Trane XL13c on my roof. Had to replace the indoor blower wheel. Had the fan motor tested and lubed by reputable local dealer. Everything put back together as it was before I got into it. I used photos and diagrams to be sure. After assembly, the thermostat was blank. Replaced the 5A fuse on the controller panel. That put all back right with the world. I tested both A/C and heating systems, up and down the temperature range about 15 degrees. Probably spent 1/2 hour running it, letting it cycle, before I buttoned her up and got off the roof. Inside, thermostat was reading temp, heat & A/C off. Two days later, I went to turn on heat and t-stat was blank again. Evidently, the fuse blew again. What should I be looking for at this point? For the record, my experience with these things is limited,but, I am usually handy and successful fixing things. Especially when I can't afford to hire help.