A/C Blower Switch (1983 911SC)

[tim35144]

I recently bought and attempted to install a replacement A/C blower switch (911-613-243-00-M100) in my 1983 911SC. The old unit is square, metal and has 5 male connection studs on it; one top center & the others 2 X 2. Each connector is marked with a letter A, B, C, etc. The new unit is plastic and round shaped w/ 5 connector studs; one top center and the others located in a circular pattern edged and marked w/ Roman Numerals- I, II, III, IV, V. I don't want to blow any fuses, and cannot find a tech page that shows how to hook up the replacement unit. I have also already replaced the front relay switch. Is it as simple as A=I, B=II, C=III etc. Please help.