You are going way off track..
The Aux fan relay and 15A fuse have nothing to do with the Blower motor ..they control the aux fan in front of the radiator. And if you were not getting power to the red at blower until you started fooling around up at the aux fan relay, I think you may have a hairline crack fuse problem at the fuse-link over at the left shock tower..that needs to be checked first as it is a common problem and may even have been you trouble from the start..check that w/test lamp. on both sides of the fuse holder. That is 12 V feed to red at motor [ test #1]. If that is the problem , you may have not even needed the motor..................
And you do not have to take the blue wire off the reg or motor ..you just place a juimper wire on the blu terminal at the motor [ step #2] and ground the other end after you have confirmed 12V at RED [ step 1] If that gets you blower full speed , then you have to see if the yellow wire at the regulator is getting variable voltage ..that is what triggers the regulator...NO V at yellow wire equals No fan b/c the reg is not seeing a trigger from the control panel. That is the regulator test and is the 3rd test , the first being RED V at motor and Jumper from blu to ground to test motor as test #2 ..you have done those and confirmed blower and power to blower , but you have not tested the reg yet....
If you would like to assume the regulator is Bad and want to change it , fine...but the correct way is to see if the reg is getting a trigger signal from the Control Panel...if it is , you are correct in replaceing the reg,... if it is not , you have just wasted some big $$$$ 'cause the new reg is not going to work any better than the old one w/o a signal at the yellow wire.....
This test sequence that I am giving you is a standard 3 part test for blower and it is all done at the 3 connector plug behind the brake booster...That allows one to check for power to RED , ground at Blk, and regulator trigger at yellow without taking ANYTHING apart..you just open the hood and do the test right at the plug.
You then know if you need to go down into the motor compartment .
The CP, fuse link, blower power feed , and reg trigger sigs can all be tested right there on top before taking anything apart.

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A Dalton