< >>

You don't have variable reading out of the reg, you have a var. voltage ONTO the reg ..that is TRIGGER voltage from the CC
The 12v wires at the reg [ red/blk] are simply supply voltage for the reg internal circuit. They do not change. EVER...
What the reg does is it controls the GROUND side of the blower .That is why I asked you to GROUND the blu wire. The blower circuit works on a SWITCHED GROUND circuit controlled by the reg. ..and that is controlled by the variable trigger voltage from the CC. When the reg gets trigger voltage, it GROUNDS the blu wire..that is it's function.
So , as I said, you go ground the blu wire at the motor with a jumper ..that takes all circuits out of the blower b/c the red for blower is always HOT. [ no switching is done on the HOT side of the circuit].. you now have a DIRECT 12V bat source feeding the blower motor for testing.. [ red for 12v pos and blu grounded for 12v neg....just like you took the blower out of the car and hooked it to a Battery]...all other controls are OUT of The Circuit..this is just a blower motor test. The blower will then spin at High/full speed b/c there are no controls in the circuit. If you wabt to get fancy, you put an Amp meter across the fuse link when you do this ground test and that will tell you if your motor is drawing too much of a load..if it is in spec, you now know you do not have a blower problem.
If you do that test, then I will tell you the next sequenced one ..which depends on the YES/NO of that one...............................