Combines Pressurization fan

What year is your 88IJ I know the '95s and '96s had an update fot the air system. they did it to my '66. the air filter is relocated to the R side of the machine, and a pipe goes thru the graintank to the l side to the cab air enterance. One guy here had a mold problem in a new '88 in 1995 the filter would get moist and mold grew and got anyone running it sick. mine doesn't have a fan under the buddy seat that I'm aware of. I had the seat out when replacing the rear window but never saw afan. hope this helps.

The fan under the buddy seat is what pressurizes the cab to keep the dust out. It runs continuously bringing outside air in. It needs to run to keep the cab clean. Tango

The pressurization fan needs to run to keep the cab clean. It will only run when the motor is running so be aware of that.