I have a whirlpool dryer, model number is WGD5540SQ0. It will heat up when I start a cycle as I see the igniter glow and the flame turn on. The vent tube will heat up as the cycle continues but never gets real hot. I would say after 5 to 10 minutes the vent tube starts cooling off and is cold to the touch. I have tried doing a timed cycle which seems to dry the clothes a little better and a regular cycle and there is no difference in the outcome of the clothes. I have replaced the thermal fuse and cycle thermostat thinking it was one of those.I also cleaned the vent tube and the back of the dryer from lint. Any help to get it working properly would be great as buying a new dryer isn't an option.