Thats a really nice one, blends really well ! 2 things though...
- Lots of jaggies, im guessing you cut it out using the 'magic lasso' tool? You should really do it by hand, your just being lazy

- The lighting doesnt really match up, ie the position of the sun compared to the lighting on the AC. Quite a simple one to fix though, just rotate the backround 180 degrees horizontally and it should pretty much sort it.
Anyways, good job ...does look very real
