I have a 3 year old Trane XR90. I've read a few other posts on this board regarding moisture frying the board. As I went to fire up my furnace for the season, my Honeywell Chronotherm IV Plus wasn't showing an display output.
The furnace troubleshooting LED was showing a slow flash which correlates to not receiving a HEAT ON signal from the thermostat. I swapped out the failed thermostat for a cheapie battery operated thermostat and the furnace immediately kicked on. The Honeywell is being powered from the board.
What is interesting is that I have an electrical outlet that is in a circuit with the board and it has failed also.
Any thoughts or suggestions would be appreciated!