I work in a commercial building that has forced hot air. The duct above my desk blows cold air more than hot air. Why is that? Also, what do you believe the temperature of the cold air is that is coming out. I have a temperature reader and it states the "area is 71" but the air that is coming out is very cold.

I believe its warmer than it feels... because of the wind chill effect from evaporation of body moisture from the moving air. The only way to know what it actually is would be with a thermometer.