Parallel. I used 1/2 watt resistors from Radio Shack, bought a pack of 1M and 100k. A whopping dollar each, btw. :p

One 100k plus one 1M = approx 91k total
One 100k plus two 1M = approx 82k total

If you are at 49F vent temps now, and your ETS is on the far/warm side of spec like mine was, I'd try a parallel shunt in the 80-85k range (90k if you want to be a little conservative). I took a photo of the mod, soldered at the stock connector housing, but haven't uploaded it to my website yet. Stay tuned, I can probably do that soon... I also have the more complete original write-up from Stu Ritter or Richard Easley. I'll post that too.

(I'm still not sure why an "in spec" ETS gives such poor vent temps... my theory is that something in the climate control brain pushbutton unit is also on the far/warm side of spec, and the two tolerances add up to lousy vent temps! Not sure if I can prove that though. )