I have a bathroom sink upstairs that I see today you can pull the handle to get water, but only a tiny trickle comes out. I had left it in a 'tiny trickle' position for many days. This was due to the potential it might freeze otherwise. I actually don't think it froze because a small stream of water comes out, but when I pull the handle all the way to release full force the stream does not change. Cartridges in faucets in this house are probably 12 years old. Any suggestions what might be causing this? It;s not that cold here (chicago) today either. Just tried the first answer - cleaned out AERATOR - IT WORKED !!!!! thanks so much!!