Earlier blower used speed resistor.. this chassis has a transistor regulator circuit.
Before going to blower/reg , check for voltage at 3 wire plug at firewall, behind booster
red to blk is bat 12v. Yellow to blk is 2-8 v. depending on panel setting Set at defrost for this test

..if no 12v , you have a bad fuse/wire feed . If you have proper vlotages , THEN go to the trouble of getting to blower/reg.
Once there , ground the blu wire on the blower . if blower starts , reg is kaput.