Originally Posted by Arthur Dalton

http://catalog.peachparts.com/ShopByVehicle.epc?q=1989-Mb-4--0sel-Climate--Control&yearid=1989%40%401989&makeid=MB%40%40MB%40%40X&modelid=420%2DSEL%2D001%40%40420SEL&catid=R%40%40Climate+Control&subcatid=R2022@@Blower+Regulator&mode=PA

See the red and blu wires that goes to the blower??
Jumper wire from the blu to ground ..if that gives you high fan, reg is suspect.
But you see that 3 wire plug?..that should have a yellow wire that is variable V from ther Control Panel..that is what triggers the regulator and if no V there , the problem is not the reg.
You should have 12V ay the red also.