remove the back half of the cabinet and as you look from the front on the righ hand side there is a clear tank.this might be blocked up.inlet valve for dryer might be faulty or open circuit.sensor wire on the pipe at the bottom of the clear tank might be broken.sensor on the top ducting might be broken or faulty.last resort would be a pcb fault but the pcb is told to do what you are experiencing if there is a fault within the system.
ck
March 2009