you need a manometer to test gas PRESSURE across the gas valve. is the valve being sent 24 volts to open? DO you hear a distinctive click at the gas valve indicative of 24 volts being sent to the valve? that would happen upon a call for heat.
post the model and serial number of the unit. is there a control board which sends 24 volts to the gas valve? if so test on the board at gas valve output to see if 24 volts is even being sent to the valve. if not, new control board.
post the model and serial number of the unit. is there a control board which sends 24 volts to the gas valve? if so test on the board at gas valve output to see if 24 volts is even being sent to the valve. if not, new control board.