At ~ 1015 hrs local time, I got an alarm that the temperature at E Y was ~ 1 degree F. above set point. I started to investigate and things were just not looking correct on my FMCS screen. I confirmed with the control room operator that I was able to go to the end station and upon entering the building, I immediately noticed the sound was not what it normally is. I looked in the air handler room and the F/B damper was completely closed. I looked at the linkage which was in an obvious bind so I forced the damper open and the temperature immediately started to stabilize. I will continue to closely monitor the temps and hope to re-adjust the linkage on Tuesday morning unless it is needed sooner.