OK you say it acts like it is going to work. Below is the normal sequence.Tell me how far it goes before shutting off.
SEQUENCE OF OPERATION
Thermostat call for heat
R and W thermostat contacts close signaling the control
module to run its self-check routine. After the control
module has verified that the pressure switch contacts are
open and the limit switch(es) contacts are closed, the draft
blower will be energized.
As the induced draft blower comes up to speed, the pressure
switch contacts will close and the ignitor warm up period will
begin. The ignitor will heat for approx. 20 seconds, then the
gas valve is energized to permit gas flow to the burners. The
flame sensor confirms that ignition has been achieved within
the 6 second ignition trial period.
After the flame sensor confirms that ignition has been
achieved, the delay fan ON period (fixed at 45 seconds)
begins timing. After the delay of 45 seconds, the indoor
blower motor will be energized and will continue to run
during the heating cycle.
When the thermostat is satisfied, R and W thermostat
contacts open, the gas valve will close, the flames will
extinguish, and the induced draft blower will be de-energized.
The indoor blower motor will continue to run for the
fan off period (fixed at 100 seconds), then will be de-energized
by the control module.