My upstairs gas furnace seems to be working half of the time.. I went up and checked it out and the gas valve is not opening. (no "click" or initial light off) I know the sequence of events is.. thermostat calls for heat, control board send signals to start the inducer fan motor, then the pressure sensor verifies that, then the ignitor heats up, then the gas valve is supposed to open and light the burners. But mine will not light the burners.. so then everything shuts off after @ 5 seconds.. no gas is coming through the valve so it's down to two things. the control board not sending the signal to the valve, or the valve itself is bad.. Every video I watched on how to test that, shows a 2 or 3 wire gas valve, but mine has four wires, so not sure which ones to check to see if the 24v is there or not. Anybody know??
