Driver seat, Passenger Seat not heating

[DATHVADER]

I have a 2010 GMC Sierra Denali Truck. For a while now my driver side stopped heating up. Lights would turn on but no heating. Now my Passenger side now is doing the same. Lights turn on. No heat. 

 

I have checked the fuses all seem to all working.

 

It is just strange that they are both doing the same thing months apart. Any advise.

[silveradosid]

common problem read this article https://www.justanswer.com/gmc/798yi-2010-denali-pickup-passenger-heat-cooled.html