Hello and welcome aboard.
Try the cooling function of your seat as well as the heating/cooling of the passenger seat.
It's also possible that your heating element is probably bad. This is one such thread I found when I searched:
https://forums.nicoclub.com/post6687161 ... r#p6687161
You could find more topics when you search for these words: Peltier, TED, TEU, TEC, thermoelectric, etc...