740A series VI heater fan

Hey there. Been working on my grader today and found that the heater fan is only running on setting 3 out of 4. Nothing happens on positions 1, 2, or 4. Anyone know where the resistor for the dual fans is located on these? I think I spotted something way back under the seat that might be it, but it's a pain to get to and I couldn't see it clearly enough to be sure. Also, the previous owner swapped one of the defrost fans for a 12v version, and that thing runs at full blast. Going to need to sort that out too.

I haven't worked on your particular model, but I've pulled heater fans out of a Cat 140 G grader. You have to get the seat out and pull everything from underneath. Fair warning though—that seat is brutally heavy. Took two of us just to get it out of the cab.

Yeah, that's what worries me too. Looks like the whole panel under the seat would have to come out, and it doesn't look like a fun job at all.

I swapped out the seat in my 730A and it wasn't too difficult—the hardest part was just getting the new one up into the cab.