I have a 2,300 square foot house with two unites. The unit in question heat/cools one side of the house, and we have a smaller unit that heats/cools the other side. My Goodman 100-3 unit (100K BTU) keeps blowing fuses. Repair guy said it was the circuit board. He put another one on it, and he said it shot the new one too. Do we need two units, what could be wrong with the unit that blows fuses and circuit boards, and what's the best way to repair it, or should we replace it? If so, how much would it usually cost?