Underskirt Blower motor replacement;
Vertical style.
 Previous

Safety Warnings!
Remove Power from the spa/hot tub BEFORE performing this procedure.  Failure to comply with this requirement, can lead to electrical shock and/or electrocution!
Disclaimer
The instructions here are intended for general reference only.  Many blowers are different from the one depicted here, and may require more or less mechanical effort or knowledge in order to achieve the desired results.
READ FIRST BEFORE YOU CONTINUE
First, remove the blower pipe from the top of the blower, this may require the removal of a single screw penetrating through the blower housing, or a pipe clamp.

Then remove the screws holding the base of the blower to the spa.  Note, that if the attachment base is made of metal, and the screws are rusted through, you may have to destroy the screws using a hammer and a chisel, or drill, or by other alternative means in order to get the blower out of the spa skirt.

 

Now, with the blower removed, put it on a work surface that is suitable to you, this could be the floor or a work bench.
Using a 5/16" or 1/4" inch nut driver (or other appropriate tool), remove the 4 screws that are holding the top half of the blower housing to the lower base.
Once the screws are removed, separate the two halves of the blower assembly.  This may require a certain amount of force, especially if their is corrosion or rust built up between the components.  In this particular example, we can see what caused this blowers demise... which is typically, water, and corrosion.
If the blower motor won't separate easily from the top part of the assembly, (which is typical), using a screwdriver to pry it out of the top of the housing usually works ok.
This is most likely what you will see....  Go ahead and separate the motor from the shell, being careful not to stretch the power wires too much. 

At this point, it may be required to remove the power cord strain relief to allow enough room in the electrical cord to remove the blower motor further.

Now is a good time to wipe the blower internal surfaces clean.

At this point, you should see the three wires and where they connect to the blower motor.  They will (should be) colored Black, White, and Green.

Cut the wires on the power cord on the input wire side of the wire nuts (wire connectors).

If the green ground connector is not corroded, it can be re-used.  Remove it from the blower motor using a nut driver, and attach it to the new one in the same place.


(To purchase a new motor for your blower, click here .)
Strip and connect the power wires together, being careful to separate and insulate them properly.

My preferred procedure is to connect the wires using wire nuts, then wrap the wire nuts and the wires together using electrical tape.  This prevents the wire nuts from spinning off in the blower.  Then I use a nylon tie wrap to secure all of the wires together and to keep the electrical tape from unraveling.

Once that is complete, push the blower motor into the top half of the housing.  Then, pull out the excess cord from the top of the housing and reassemble the strain relief in the housing to retain the power cord.  If you didn't have to use any more cord to attach the power wires than was required by the original motor, then the strain relief should be used in the original position on the cord as when it was removed.
Reassemble the blower housing using the original screws.

Then VISUALLY inspect the wiring from the blower exhaust to ensure that the wiring doesn't interfere with any part of the armature (moving part) of the motor.
 

The next step is to remount the blower and reattach the blower pipe as it was originally installed. 
Next, I make sure everything in the vicinity is dry, so as to prevent electrocution, then plug the blower back into the spa control and test for proper operation.