genereral electric dryer runs but dosent dry?

ok i turn it on it will dry for a few minutes and then just cold air comes out the exhaust in the back, then i turn it off wait 30 to 45 minutes and the same thing it will dry for 3 to 5 min then nothing just cool air , now on the front of this dryer it says heavey duty general electric automatic dryer then on another part of the dryer it says permanent press with cool down ok there are no places with a model number or and other identification marks that i can see.