Behind the brake booster, on the firewall , there is a 3 wire connector.
Red/Blk/Yl.
Here is the test @ that connector:

Key ON
Defrost position

Blk[neg] to Red [pos]=12v.
Blk to Yellow - variable voltage ..from 2-9 v , depending on fan contol setting.

That yellow wire is the trigger wire signal to the blower Regulator.

See what you have at this connector ..if all is well , you have to go to the blower and check for voltage at the RED wire of blower ..That should be 12v w/test to ground. [ always hot]. If yes , then ground the Blu wire at the blower [ just a jumper wire to ground]. If High fan with jumper , you have a bad Regulator..if No fan with jumper , you have a bad blower motor

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A Dalton