i do not have the model number available. this is a 3 toncarrier weathermaker gaspack. i can not get the heat to operate. when the thermostat is calling for heat nothing happens. i checked voltage on the terminal board and it is calling for heat. i can jump out r&w and the draft motor runs and the burners ignite. i can jump r&g and fan runs. but i can remove tstat from unit and wire heat and fan to r terminal and nothing happens, unless i pull the pin from the board that goes to the rollout and limit the fan and draft motor start but no burner. what am i missing here? i have to admit i do not work on much heat. i checked limits and rollout switch they are good. any help is appreciated.