My Lennox Pulse 21 furnace will not turn on. I can hear the thermostat click on but the furnace it self does not turn on. I replaced the filter and fuse. I also reset the furnace by the switch on the blower housing. The fan will come on if I turn it on at the thermostat but only cold air comes out.

My lennox pulse furnace will NOT kick on.. it tries.. I've followed the instructions on the fan door.. shut off the gas at the internal valve, waited the 5 minutes, turned the gast valve back to "ON" then turned the power back on.. the furnace tries to "kick" on.. but shuts off and then will not run.. is there a ballist(sp) that maybe not funtioning or what... I don't like the idea of calling the "dealer".. what are the steps to fix it myself?