The Archer I fly is older and does not have the Temp right there on the side. It has an electronic one with EGT/Temp/CHT. So would that side probe be the one that it is receiving the temperature from?
Yep. However it may not be providing any information to your modified installation. You would have to check the drawing that came with the STC to know how it is supposed to be connected. (Notice I said 'supposed"?)
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward" Leonardo Da Vinci