HeyU, My FSM says to run what they call a "Blower Feedback Test".
Measure Resistance at Heater and A/C Control Assembly Connector (Disconnected)
Ignition Switch must be OFF.
Connect a fused jumper across Blower Motor connector terminals A & B
Measure Between L(PPL) & Ground
Correct Resistance should be less than 3 ohms.
Check Relay Center Fuse 1, PPL (65) wire and ORN (761) fir an open or short to ground.
If Resistance is correct, check GRY/BLK (754) wires for short to Battery. If wire is OK, replace Heater and A/C Control Assembly.
BUT, This info is from my 91 Olds FSM. Although our cars are kiss'n cuz'ns. Things are not necessarily the same. I'm sure the Electrical Guru'* will give you additional info on your problem. Good Luck.
Oh, and Welcome to the Bonneville Club.
2006 Salsa Vibe
2002 Snap Orange Beetle - Turbo
1991 Olds "Orphaned" 88 - Donated to Science!