I have a carrier crusader model number 58ssc075-gc. I am getting no heat, when I self test by touching a penny to the 2 self-test posts, the small black fan at the top of the unit comes on, the ignitor becomes hot, I hear what I believe is the click calling for gas, then nothing. When I call for heat with the thermostat, the big fan comes on for about 15 seconds and then nothing. I am not sure what to do next. Any ideas will be helpful as I am a single mom with 4 kids and we are freezing. Thanks in advance