Smoke in cab - burning eyes

Update 2**

Please check picture on page 3…. I think it’s way worse than the heater

Update**

****Lifted the hood and didn’t see anything that had obvious signs of melting/burning. Checked the batteries and they’re dirty but not wet or overheating. I saw the white smoke again coming from behind where the dash is in the engine compartment. I turned truck off immediately so not much more I know other than it’s gotta be something in the dash right? ****

2012 Volvo with bad batteries and sitting in -2• weather. Have to start my truck every few hours to keep the batteries from giving out and this last time after about 10 mins I pulled back the curtain (I was laying in the bunk) and there was smoke and a burning sensation in my eyes. I think it’s coming from the heater but I’m new to this and don’t know where to even start looking. Gonna wait until daylight to get under the hood, but would appreciate some ideas on where to start. As for the batteries, they’re on the list of things to replace/repair when I head home in a few days.

 

I’m not turning the heater on when I’m running the truck, it’s in the off position. I have a bunk heater so I don’t need to idle the truck. I’ll look up some information on that switch and see if that’s it, thank you

 

Not sure which vent it’s coming through, I’ll have to turn it on to watch it and then go from there.

 

I don’t believe it’s an exhaust leak (which was my first thought). I’ll make sure to check for the black soot though just in case.