2020 Cummins 2500 noise I've never heard before, heater related?

[Highcountry]

I've been hunting the last couple weeks, driving alot on gravel roads and have the radio off most of the time. This morning I heard what at first sounded like a ticking sound from the passenger side front. As I listened for it more it became clear it wasn't relatated to moving at all. It sounds like its in the dash behind the glovebox. Almost like a peculating sound. heater core maybe? I only have 10k miles on this truck, but haven't noticed this sound before. All my temps are normal, just his weird sound

 

[flan]

Does it only happen with your HVaC fan on?

 

[Highcountry]

I believe it also does it with fan off. I'll be using it this week and will see if it repeats.

 

[flan]

Ok I was wondering if something got into your fan housing or the cabin filter was fluttering, tough diagnosis over the www.

 

[Brutal_HO]

Could it just be the EGR valve you're hearing?