fair market value for 84 heating system control mechanism?
 

It works, and is in great shape. NLA part. Did a search but maybe there is a more common name?

911 659 053 00 - heating system control mechanism (manual)

http://i1168.photobucket.com/albums/...ps1tr3f94w.jpg

http://i1168.photobucket.com/albums/...psbqw1wqla.jpg

Here are three that recently sold on eBay at $300 plus . . .

http://www.ebay.com/sch/i.html?_odkw=porsche+911+auto+heat&LH_Complete=1&L H_Sold=1&_osacat=0&_from=R40&_trksid=p2045573.m570 .l1311.R3.TR3.TRC1.A0.H0.Xporsche+911++heat.TRS0&_ nkw=porsche+911+heater+control&_sacat=0

For some reason it looks like the link doesn't work, but if you do an advanced search on eBay for "sold listings" using words such as "911 heater control, auto heat, etc." you can get an idea of its worth.

Although this is not an auto heat control module, correct?

it is auto heat
 

As auto as heat gets in a SC or Carrera