http://forums.vwvortex.com/showthread.php?3622612
If you are going to seriously undertake this, do your homework. Good luck.
What you need:
1. Climatronic airbox - complete
2. Climatronic controller (knobs) + radio trim
3. Dash sunlight sensor (my '06 has one factory installed )
4. Additional temp sensor for passenger side
5. Harness - I used OEM harness, but it is not difficult to make one. You need to wire the sunlight sensor and temp sensor. All other wires are pretty much there, just different pin configuration. I have soldered just one connector from climatronic harness to my car (plus added the wires mentioned above).
6. Bottle of G12 coolant for refill
Other things you need:
1. Scheduled service of discharging/recharging AC
2. 2 clamps to clamp disconnected heater pipes
3. 2 new seals for evaporator connections
4. Few feet of I believe 1" rubber tube to blow coolant of the heater core and pressured air source. Be careful when dealing with coolant; it is a DANGEROUS POISON!!!.
5. Small hands and flat M10 to reach one bolt the airbox is attached to the wiring retainer on the passenger side. An alternative is to remove the whole dash supporting bar, but I did not want to do it.
Quick how-to:
1. Discharge AC
2. Remove dash (removing dash is a piece of cake, removing central console is a effin PITA) with all elements blocking the airbox from removing
3. Clamp heater pipes and disconnect them (PITA to pull them out). You will need plenty of rugs to avoid spilling. Blow coolant off of the heater core with pressured air.
4. Disconnect AC pipes (2 bolts)
5. Remove 5 bolts attaching airbox to the dash supporting bar. Pull out the airbox, avoid spilling coolant (it is still in the heater core).
6. Optional step: disassemble airbox and pull out heater core, evaporator and PTC (if applicable). Install them in the climatronic airbox. I did it, as the donor heater core and evaporator were damaged. Plus I did not want the contaminate AC and cooling systems.
7. Reinstall the airbox. Put the rubber seal on the firewall first.
8. Reconnect AC pipes. Make sure you install new seals and the whole connection area is clean.
9. Clip back heater pipes. Make sure they are well seated. Remove clamps.
10. Wire the temp and sunlight sensors
11. Reinstall everything else.