Does the blower stop before the end of the delay ?

If the blower of your towel dryer stops before the end of the delay, it's possible that the air intake at the back of the appliance is slightly obstructed, perhaps by dust. Clean this area as well as the filter of your appliance if it has one. Refer to the "Advice and Maintenance" section of your appliance manual to learn the maintenance and cleaning procedure for the filter.