The blower positive terminal is always Hot, the switching is done on the ground side of the circuit..[ referred to as a switched ground]
So, by hooking a wire to the blu wire coming out of the blower and grounding it , you have completed the blower circuit without the regulator... if the blower runs, you have a reg circuit problem.. If blower does not , check for power at red terminal of blower and if yes, blower is bad..if no power at red , check feed/fuse circuit. If blower checks out yes with jumper, then you have to check that the reg has trigger voltage from the control panel . This will be 2-8 V. at yellow wire [ depending on CP settings]. If there is V at this reg trigger , you have a bad regulator. If no trigger , you have a problem at the CP
A note:
If the reg is found to be bad , I would check the blower Amp draw wired direct to assure it is within spec [ 25A.] If it is higher, that will burn out the new regulator.. Out of spec draw is usually caused by bad/binding shaft bearings or worn brushes.
It is also possible to have a bad reg caused by a plugged air filter system, as the heat-sinz dissapation requires air flow from the system to keep it in check.. so check both of these conditions before installing a new reg. or you can burn up a new one in no time

PS
I always use a jumper with an in-line 25A fuse in the jumper just in case the blower is shorted/bound , for protection of cars harness/feed.