The records show that a $250 climate control unit was recently replaced. p/n 126-830-05-85. Is this the ACC switch set or something else?

Where the trap oxidizer would be is a pipe wrapped in aluminum looking heat shielding. Is this a plain pipe or does it serve an emission control purpose?

Thanks,
Sixto
91 300SE
87 300SDL (correction on year)
81 300SD (for sale cheap)