Condensation dryer with a heat pump and recognition of an impermissible operating state and method for the operation thereof

A condensation dryer having a temperature sensor to measure a temperature of a coolant; a first comparator to determine a temperature difference between a first temperature of the coolant and a second temperature of the coolant that is measured after a period of time and to compare the temperature difference with a limiting temperature difference stored in a controller; a counter to ascertain a number of occurrences in which the temperature difference is greater than or equal to the limiting temperature difference; and a second comparator to compare the number of occurrences with a limiting number stored in the controller and to evaluate a number difference between the number of occurrences and the limiting number with respect to the presence of an impermissible operating state. A first impermissible operating state is indicated if the number difference is greater than or equal to a value stored in the controller.