having issue with my furnace. A trane xe90. Home is new to me so I have never run the furnace before. AC works great with no issues. Furnace issue is: Tried to turn the heat on, and exhaust vent fan kicks on, burners light and go for a minutes or so (preheating I assume) then before blower kicks on, it trips the breaker. I do not havea problem with the blower coming on for the central air, used that all summer. thought maybe thermostat wiring was wrong so I disconnected the thermostat completely and just ran a jumper to give the furnace a call for heat and it does same thing. Vent fan, burner, trip breaker... what the heck could be wrong? would just running the jumper make it work or does something have to be hooked up to the terminal for blower too?