Please provide a few more details. Do you mean when you turn thermostat to heat, everything comes on, then shuts right back down?
The t-stat is set to heat. The furnace will turn on and then immediately turn off and keep trying to turn on over and over. I can hear clicking from the board during this time as well. The light comes on, on the circuit board and goes out when the furnace turns off. On then off. On then off. What is weird is as soon as it kicks on, if I turn the t-stat to the off position it will stay on much longer. Then time out and turn off.
Do you have a volt meter to check and see where we are losing power?
Check the high voltage connections where they wire nut to the furnace wires and make sure they are not loose
Ok it seems like all is good up to the control board.Are you getting a flash code from the LED on the board when you turn power on?
If the 120 is steady to the transformer and the 24 volts is steady from the transformer I am going to say you have a problem in the control board.However, this board runs a couple hundred bucks, so I would recommend having a tech verify before replacing the board