The behavior of a PTC heater

These pictures show a PTC heater self-regulates its temperature and current consumption.

In this setup the repeatable thermal switch mounted on the PTC heater is bypassed, so the whole heating & cut-off process relies on the self-regulation characteristic of the PTC heater.

The PTC heater draws the max current while initial heat-up until its max temperature about 350℃. During the process its resistance increases and power consumption gradually drops to zero amp.

The fan is then switched on. The heater is cooled down and its resistance decreases, again starts drawing current until the heat generation and external cooling reach a balance point.