**Applies at least to 1995 Bonneville SSEi with Electronic Climate Control**
After looking for instructions all over the web, getting them and actually doing the job, I can tell you they were all wrong!!!
Here'* how you do it :
-Remove the heater core'* hoses from under the hood
You have to remove the cowl. The hoses are very badly placed in a tight corner. I personnally used a special tool I bought on ebay to get to them. It'* the hardest part of the job. If you can't do it, stop working, get proper tools and try again.
-Remove the passenger side kick panel
-Remove the glove box and it'* door to gain access to the heater cover'* top screw and heater door motor wire socket.
-Remove the Programmer. It'* the last part on the right of the entire heating/cooling assembly.
You'll have to use a long socket 9/32" to remove the center nut holding the vacuum hose assembly.
Remove the wire assembly.
Remove the 2 bolts holding it. One is easy to see, the other one is upper and you may need to fiddle a bit to get it out.
Lower the assembly (and hold it with your left hand) just enough to pass your right hand. Reach on top of the assembly, you will feel a wire loom. Follow it with your hand and remove it'* socket from the heater door motor (there is no socket on the programmer side, wires simply go out the box) on top of te heater cover. You may pass a small screwdriver from the glove box hole to pry the holding clip while pulling.
You can remove the programmer now.
-Remove both heater cover screws. There are only screws on trunk-side of the core.
-Fiddle with the heater cover until you can it out of there.
-Remove the holding clip that holds the heater core in place.
-Remove heater core.
Installation is reverse procedure.
You can reassemble the heater cover with silicone or something to make sure there wont be leaks.
Be warned you WILL have a hard time putting the cover back in there. Be careful not to damage the heater core while putting it back. Rest is easy.
Sorry if some things don't make sense, english isn't my primary language.