A\C Problem

I have a 2001 Ford f-150 with around 33,000 miles. For the first time of the year we used the A\C today and while it blew air cooler than outside, it did not blow cold air. After about 20-25 minutes of driving it started to cool down a little more but not much. What could be causing this issue and is it something that I can correct on my own?

Thanks