Hi I have a gas furnace the blower will not come on sense I replaced the Thermostat everything else work but that will not come on.:confused:

What type of heat gas furnace, heat pump? If you turn the fan switch on the thermostat to on will the blower run?

What do you mean by " Everything else works" does the pilot lite or is it already lit? Does the burner come on and burn for four or five minutes, and the en the blower is suppose to come on but doesn't. Then do the burners turn off and stay for several minutes and then the gas comes back on and it continues to go through this cycle until you turn the thermostat off??
If it does all of this then you need to suspect the motor first. If you have a volt meter check to see if you have voltage going to the motor. If not check your wiring at the thermostat. It could be that the green wire that turns on the motor relay is not connected right. Several different things could cause this problem. You just have to check them out, if you get more info let us know shat you have found.