Jetson Xavier fan inverted

Hi everybody,

I have a strange problem on my Xavier Dev Kit:

For testing purposes, I’m running the Xavier with a complete image of a hardware supplier (I am testing a camera solution of them…).

Unfortunately, it seems they have changed some things of the standard image.
The Jetpack Version is 4.2.

When the Xavier starts, the fan gets up to full speed and stays there, even with a temperature around 25 degrees.
First I thought that there is running some startup script to do this, but I didn’t find one…
When running jetson_clocks, the fan stops.

I installed JTOP and the fan speed there is inverted, too.
Low temperatures show a low fan speed, but the fan is running at high speed.
High temperatures show a high fan speed, but the fan is running at low speed.

Before installing this custom image, I used the standard image and everything was fine, so I think the hardware is OK.

So here’s my question:
Is there an easy way to find either the source for the inverted fan or to invert the fan?

I want to avoid uninstalling the delivered image from the supplier as I want to easily test their cameras.

Thanks in advance!


A quick way that to check this property is checking the runtime device tree.

You could search “pwm_polarity” which should be under a node “pfsd” in path /prod/device-tree on your xavier.
If this value is 0, then the fan polarity is not inverted.


thank you for your response, I switched to the standard image as

  • I do not exactly know what the hardware supplier changed and
  • testing the cameras of the supplier is no longer important for us

ok. If any further problem, please let us know.