There are some electronic components under the drivers seat under a panel that control the heated and ventilated seats. I would open that up and see if see anything is out of the ordinary, like for example water damage, excessive dust, etc. Maybe also check and see if any wire harness came undone or are loose. I can't really see the seat needing to be replaced in this situation.

If you see nothing out of the ordinary, I'd take it in to a dealership and get a definite answer

Edit:

To note, these seats don't blast air from them like the A/C does, if that is what you were expecting.

Sent from my SM-G988U using Tapatalk

 

Noticed mine weren’t really working either. Tested to see if the heated were working, and couldn’t feel anything. Will probably take it into the dealer tomorrow.

 

The service parts (fans) are available.
My ventilated seat hasn't been working all that well lately, but I haven't put any thought into how to diagnose it without taking it apart..

It'd be warranty if mine needs to be fixed, but if it doesn't I'll get hit with the "diagnosis fee"

 

The ventilated seats blow cabin air only. Meaning if you had the heat on, they'd blow hot air. The ventilated seats also tend to heat up slower then non-ventilated seats.

 

I could be wrong but I would swear the ventilated seats are actually sucking air through the perforations and shooting it out the bottom of the seat. No connection at all to the HVAC. When I put my hand on the seat while vent is on high, you can feel a really light pull on the air, like wicking away moisture off your back. As for heat, on low it takes forever to heat up, so I start on high and once I feel it switch to low. You should be able to hear the fans on when in ventilate mode.