Not too bad. You have to remove your dashboard, swap the center vent from a 99-00 into it. While the dash is out, you have to swap the heater blower box also, and the entire harness out. The thermostat pulley will have to be swapped with the 99-00 electric motor, which on some 96-98 civics will bolt on. Mine unfortunately didn’t, so I had to drill and ziptie it on. Be prepared to be lieing on your back while doing that. Once that is done, you have to splice your rear defroster wire into the new 99-00 main harness.
The 99-00 center bezel will sag though, you have to mod a bracket so it stays put.
Took me a few hours. Dashboard is a pain in the ass to take out of the car due to weight and size (almost impossible not to scratch interior), some people just leave it in and lean it against the seats. I took out my passenger seat so I could lie down and work on the electric thermostat motor.
Honestly, hardest part was just finding a parts car to remove what i needed. I had to drive to Chicopee, MA to get mine. :banghead
oh yeah, bump.