Nathan T Cambridge , MD June 14, 2015 Appliance: Frigidaire Room Air Conditioner LRA257ST21 Frigidaire Air Conditioner Lra257st21: Led display became garbled buttons unresponsive. How to replace Electronic Pc Board. Replaced the control board and now the unit works like new. I stored the A.C. unit out in the garage over the winter , not thinking that electronics do not hold up well in the cold. I believe that is why the board went bad. Freezing temps. probably ruined the capacitors.This year i will still store the unit out in the garage , but keep the faceplate of the unit in the house. 1 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: Less than 15 minutes