This is a old thread, but I recently used it to diagnose and repair a passenger side hot only issue and want to add some minor updates.
1. A 9/32 socket can be used instead of a 5.5mm socket to remove the actuator
2. Grand Prix actuator will not work in the Bonneville. The have the same case and look, but the connector pinouts are different.
3. I pulled the actuator from a Park Avenue at a junk yard for $10. They asked for $17, I offered $10 and they took it (I hate negotiating)
4. I could not get the actuator to slip back onto the control door tuner. Had to open the case and move the gear so it would line up. Very easy to do.
5. The actuator will not turn if not connected to the control door turner. I hooked up the electronics and then turned the temp control the motor did not turn. Put the actuator on the control door turner, and turn the temp control, it does turn. No idea why, maybe a ground issue?
6. This thread was for a Bonneville GXP, but the SSEi (2000-2003) is the exact same procedure. I did this on a 2001 SSEi.
7. Overall very easy repair. The key is to get the replacement part cheap. AutoZOne wanted $139 plus tax for the part.
2001 Bonneville SSEi, 219,000 miles.
Whats in my driveway:
1998 Chevy S10 4x4 ZR2, 1999 Olds Bravada, 2001 Pontiac Bonneville SSEi, 2007 Ford F-350 regular cab 2WD, 2008 BMW 335i coupe (Wife'* replacement for her Bonneville). The Bonneville is my favorite of all the cars in the driveway.