INSIDE MY TRANE XL13C Is a blinker light that blinks twice ( 2 ) times
What does it mean

The flash code should be on the control panel or on a chart on the inside of the air handler door.
Here is what I found. These are Trane codes but not necessarily for your model which I believe may be a heat pump or dual fuel model.

LED Flash	Error
Flashing Slow	Normal No Call for Heat
Flashing Fast	Normal Call for Heat
Continuous On	Replace Control
Continuous Off	Check Power
2 Flashes	External Lockout (Retries or Recycles Exceeded)
3 Flashes	Pressure Switch Error
4 Flashes	Open High Limit Device
5 Flashes	Flame Sensed when NO flame should be present
6 Flashes	115 VAC power reversed polarity or poor grounding
7 Flashes	Gas Valve circuit Error
8 Flashes	Low Frame sense Signal
9 Flashes	Check Ignitor