pilot on, blower not,no heat

[callee]

i have a pilot light. blower wont come on (unless i force it on by flipping switch to fan then it works)
so basically i have no heat. i have changed the gas valve no good. i read about checking to see if the gas valve has 24v going to it. if it doesnt. then what do i do?
or anything else i can check.

[Hube]

I don't think you are aware of how a furnaces cycle works, at least not by your description of a problem. In the HEATING cycle,the burner will fire, and shortly after, the fan should come on ONLY after the BURNER has first put enough HEAT into the furnace.The burner will stay on until the room temp is achieved (thermostat setting)... The blower will then continue to run until the heat is distributed until it reaches the fan's preset "Off" setting.Then the fan shuts off. Cycle finished. The fan can be activated when put to "ON" at the thermostat, but this has nothing to do with the "heat cycle". Maybe you could post back with a better detail, and we will try and help. Hube

[fdan20165]

Lennox g12 furnace- furnace lights but no air. Blower does not appear to be working. Set thermo to fan mode, but hear loud buzz from unit. Belive it might be the blower motor. Anything else to look for or try?