i had a 1990 acura legend my blower motor was located under the passenger side dash board
You need to specify what 1990 Acura are you swapping an NSX motor into.
The fan motor has probably failed.
Some parts are, the 2.7liter is but some of it's electrical components are not
In the gas tank
Worn or damage electrical motor, rotate the motor, movement should be smooth. You can always take it out and test it with the car battery. Be careful because if the motor is shorted it will become very hot.
Postive battery cable should connect to the starter relay (solenoid)
it is located under the glove box remove panel under glove box and the blower motor has three screws and two wires takes about 30 minutes
Remove the belt from your 1990 Acura Legend alternator. Remove the wiring harness from the back of the alternator. Remove the alternator retaining bolts. Reverse the process to install the new alternator.
Sounds like oil filter is the least of your problems
The transmission filter is not in the pan like most other vehicles. On a 1990 acura legend it's an inline filter kinda looks like a fuel filter but located by the radiator.
one is in the bottom of the raidator back side, and the other is on the top of the motor that is where they are 4 the 91 anyway