Our central A/C completely stopped working a few days ago. After a lot of troubleshooting, I found melted 120 V wires and connectors inside the terminal box in the unit in the attic. Repaired those, then found that the furnace control board 3 A fuse was blown. I replaced the fuse but the board was completely dead. So, I replaced the board with a Honeywell S9200U1000 universal board (the original was a York 031-01972-000). Now, the new board also blows its 3 amp fuse (twice) and nothing still happens. I replaced the run capacitor in the blower, then hooked the motor (high speed only) directly to 120 V. It ran just fine. I'm thinking there must be a short somewhere?

I'm also curious as to how the low voltage (24 V) wires hook to the new board from the thermostat and from the contactor coil in the outside unit. From the thermostat, there are white-green-red-yellow wires; from the contactor coil there are two (yellow and red) wires. On the new board, the low voltage terminal strip is marked: C/3 = 24 V ground; R/2 = 24 V hot thermostat; W = thermostat heat input; G = thermostat cont. fan input; Y = thermostat cool input.

Any guidance is appreciated!

Is your outdoor unit a york also

The short will probably be your two wires going 2 your outdoor unit , disconnect the 2 wires from airhandler board you replaced and see if fuse blowes again