Hi! It can be caused by two things:

1) Your fan on the hotend (the one attached to the hotend) is not running. Not the one that blows on the printed parts...that is not the issue.
2. Your nozzle is most likely clogged. You can clean it by opening the filament feed (remove the screws and open the hinge). Then with the extruder at a near temp of about 170 pull the filament out... Failing that you will likely need to remove the brass nozzle (which should be done hot) that will allow you to completely clear the clog.

Let me know if this solution works for you or not.