Reverse current with Peltier (TEC)
No, the circuit does not contain a full bridge.



Think of the TEC being L1 in the image. To make the TEC switch from one side cooling to that same side heating current needs to flow in the opposite direction through the TEC. One direction would be Q1 and Q4 ON and the other two transistors OFF. To switch current directions turn Q2 and Q3 ON and the other two OFF. 

Since this circuit only contains one transistor the TEC cannot have its current direction reversed. It looks like your code will just shut off the current altogether.