Have you tried disconnecting the vent from the dryer and running a cycle with a window open? Does it dry OK if you do a manual timed dry? If the clothes are not drying, but there is heat getting to the drum, the most likely cause is restricted airflow. Dryers use airflow to dry close, not high temperatures so you must be sure the vent is clear and adequate for your model. Long runs, many bends, bird living in the end will all cause poor drying.