There is an awesome thread on a site ?outers? on how to clean the core out. I did it on a mates zook, worked a treat!! Basically you find the right spot on the passenger side of the heater box (above where the join mark is for memory?) and you drill out a circle using a hole saw. Then, you get in there with air, a soft brush, vacuum cleaner etc. Once done cleaning the crap out (most likely be leaves and dirt and sand etc), silastic the cap back into the hole. Works a treat!! My mates had no air flow at all.. but once done, it was like a new one
