I have checked my seat filters and they were fine, too. The cabin filter DOES get dirty. Our heated/cooled front seats are a different design than cars that have heated only seats. The heated rear seat is the conventional kind that does get warmer. My fronts get plenty warm but take longer to heat than cars with conventional heated seats. Here is something I found when I researched this some time ago. This is referencing a Lincoln Blackwood but ours use the same system.
The core of the system is a solid-state device called a Peltier circuit that is integrated into a miniature heat pump in each seat.
The Peltier circuit is named for the 19th-century French physicist Jean Charles Athanase Peltier who discovered the concept of thermoelectric reduction of temperature - that a positive electrical charge generates heat and a negative charge absorbs energy, producing a surface that is cold to the touch. The U.S. military uses Peltier devices to spot-cool heat-sensitive electronic devices.
The Peltier devices used in Blackwood are made of a high-tech sandwich of the metals Telluride and Bismuth. An electrical circuit switches polarity to either heat or cool the surface. The heat pumps, which are not much larger than a deck of playing cards, force heated or cooled air over the surfaces of the Peltier devices and to the seats through flexible ducts. The heated or cooled air exits through the perforations in the leather seating surfaces. The Peltier devices themselves have no moving parts, and the system uses no environmentally sensitive CFCs or other coolants. In operation, the system is very quiet - about 45 decibels - far quieter than the 65 decibels generated by a typical automotive air conditioning system.
