Here's what's going on.. this doesn't happen all the time just sometimes.. my thermostat is set at 67 and the room temperature is 67 so why does my furnace keep coming on but not completing a cycle ? It will come on and what I guess is the first stage the burners fill with gas and right before it would normally light it shuts off and doesn't light ( I did replace the ignitor) the blower comes on than turn off and immediately this process will repeat and this will keep repeating itself until I shut the furnace off at the thermostat or raise the temp setting.. can this be a bad thermostat? Because I don't see why it would even turn on if the room temp is what I have the thermostat set at..