I just got my dash all back together after replacing my heater core ( wow what a pain ) and now for some reason my blower wont kick on. I took my time and made sure I hooked everything back up but I'm not sure what I could have missed. I checked the small harness with the blower wires that come up behind the glove box, it has a green plug, checked all the vacume lines, the 3 big plugs under the steering column..... what else could there be? Oh this is in a 2000 XJ, and yes it worked before hand.

 

I just did this job on my 2000 so I know what you went through. Double check the actual connection on the blower motor, unless you did and I am not reading your post correctly.

 

Did you possibly trip a fuse when you reconnected everything?

Also, I hope you also replaced your evap core also. I know your pain because I just did my evap core, and preemptively replaced my heater core because I didn't want to have to have to rip out the HVAC box twice.