Thanks for the feedback!

The furnace can execute the full cycle as described, reach to the target temperature, and stop. 

Till here everything looks normal.

The abnormal situation is after the furnace's stop:

After the furnace stops for 1-2 minutes AND the room temperature is still at the target temperature AND the themostat does NOT send heat signal, the blower motor will somehow starts for about 10-20 seconds and stops. The blower motor will repeat this for 2-3 times with a 1-2 minutes interval and then it is back to normal until the room temperature drops below the target temperature. 

Based on various feedback and online study, it appears that the control board is malfunctioning. 

Will update how it is goes.

Appreciate all your help!