I recently replaced a blocked check/ purge valve into charcoal canister and did a smoke test. There’s a line going into this thing . Not sure what it is.
I think it’s a Vacuum reservoir.
Looks like it mixes some cabin air and evap from air engine air intake. Its sealed so have no idea if theres a filter in there . I assume there should be.
Me too. Assures steady vacuum for the climate control and heat valve.
Carl
Also the power brakes vacuum booster.