Unknown smell/fume coming from vents ( 2020 freightliner Cascadia)

Smell like rotten eggs or sulfur??? If so it's your batteries going bad and venting toxic gasses.

 

Something died in the air vent?

 

What Cattleman said.
If it smells like boiling kitchen sink dishwater, you are following a truck that is ‘regening’ while going down the road.

 

Make sure you see water dripping out of the a/c vent line with the a/c on, if not you can clean it out with a air line blowing into the drain line- a little bit and water should start running out, if when you wake up with a/c blowing warm air out of the vents turn off the motor and watch the drain line for 10 min. and if you start to see water start pouring out the a/c is freezing up and you need parts replaced to make the a/c comp. shut off before it starts to freeze up and then turn on again?

 

I have the same issue with my 2020 Cascadia, but to a lesser degree. Whenever I engage the a/c, whether the blue or green light comes on, there is a stifling odor that emerges. So, I always have the windows down first to combat this.

It's always like that for any vehice I drive, but the 2020 Cascadia has been the worst.

 

if you leave it on re-circulation all the time ,you can have mold growing in the vents.

I would hardly ever have the recirc button pushed.

I like fresh air.

 

This smell occurred when the tractor only had 600 miles on it.

 

Check/ change the cabin air filter.
Have the shop open up the condenser and clean it out and check the drain holes. Also check the coolant pressure.

 

check to see if its draining the water under the sleeper. the drain can get clogged up. u see this a lot with apu's. left bed and find the hvac box. stick coat hanger threw drain and wiggle it. the pooling water around the evap and dust cause that wet dog smell. also check the filter under there or in the cabet