Blower motor no high speed 98 Bonnev
 

I have a 1998 Bonneville, A/C,no automatic temperature control. The blower motor went bad about a year ago, replaced it,all good.
A few months later it quit again, problem was poor connection, at the connector at the blower. Repaired that and replaced blower motor also as connector was burnt.
Haven't had high fan since last repair/failure, works on 1,2,3 but when on 4 runs at speed of 1.

Anyone have a schematic, or know exactly what causes this scenario?

I'm thinking I have a high power feed that is open @ a fuse likely, I have no idea which fuse is which.

Check the blower relay, its only energized at HIGH speed. Check your voltage at the blower motor, when turned on to High, Purple wire, be sure it has 12V. Black wire should read "0" volts (ground). The Purple wire gets power from A/C Fuse 3 (30A) underhood relay/fuse box/ right side. High speed gets power directly through the relay, all other speeds go through the resistor. The Blower relay is the 3rd one on the firewall I believe, there may be other relays you can swap and see if the blower comes to full speed.