if its vented then check theres not a kink in the hose or that the grill/mesh that usually is fitted to the outside wall is clogged with fluff.if its a condenser t/d (one with a bottle)check the removable heat exchanger at the front.run it under a garden hose front to back,and side to side.if doing so dislodges a lot of lint then thats the problem.
chris
March 2007