MacBook Air charger not consistently charging

[themoondevil]

I own a mid-2011, 11 inch macbook air and lately my charger (60w L-shaped) has been switching from red to green light even when its not at 100%. This means that the macbook charges very slowly overall (as it only seems to increase its % when the color is red). When the macbook lid is closed however, the light just remains red and charges as normal. I had a friend come over to test his macbook with my charger, and my macbook with his and the problem is definitely the charger and not the battery. It also seems that when I run more intensive programs (even youtube videos) the green light shows up more often. So I had concluded that there was not enough power going into my laptop from my charger that it could not charge and power the active programs at the same time. Does anyone know how I can fix this, or other conclusions that could be the problem? There is no visible damage to the charger, and its relatively new (6 months)

 

[Newtons Apple]

Running your Air while charging can and sometimes does exceed to output of the charger and will result in it using the charger and battery power.