1980 300SD heat/air issues

[DNutgrass]

My 300SD w116 doesn't put out heat or air. I'm not a gearhead, and my mechanic says that the "climate control module" or whatever isn't made anymore, but that someone makes a replacement part. With labor, it's around $1,700.00. I'm not in any hurry to get this fixed (still getting my driver's seat paid for), but can someone clue me in on what he's talking about, and any alternative that I might have.

This car runs pretty good, and only has 173K. Lots of little stuff to fix, but I intend to make a driver out of it. Thanx for any help.