Because the drum is turning & the heater is hot but no air is flowing through it to take away the heat. You can confirm that by putting your hand over the outlet on the back left hand corner while the dryer is on. You should feel a strong air flow coming out of it. If there is no airflow, take the long black plastic cover off the back panel. Inside is a rubber belt. It will be either broken or has come off the pulley. Get a new one and put it back on to the two pulleys. It is very tight and you have to stretch it from one to the other pulley.
Lincoln Appliance NZ, May 2015
