[TonyTuy]

I have a york diamond 80 furnace was running great till 2 days ago, whenever the thermostat call for heat it startup fine then 30 second later the system would shut off and make some sort of clicking sound like a stuck relay, I changed out the flame sensor and saw one led flash, I shut everything off and let it reset and now no led light and nothing come on. Before whenever the heater make the clicking sound I can switch to AC and everything would run fine but now both AC and Heat doesn't work at all and no led flash, would this be a bad control board or a bad door switch which I changed and was giving me problem during the summer months?

 

[Bitters]

Check the 3 amp fuse on the control board.

 

[TonyTuy]

I changed the 3 amp fuse and no power still, I even took out the high limit switch and tap on it a few time incase it was stuck open, the LED light is not on at all so there is no power coming into the control board I am assuming

 

[beenthere]

Make sure you have 120 volts coming to the furnace. And then check to see if the transformer is working.