Wow, only 8,000 miles? Like to swop??

Before you opt to replace the CCU I'd suggest checking the monovalve as it sounds like you are getting excess heat that is competing with your AC system's ouput.

It would be helpful to know if you are getting HEATED (as opposed to ambient) air if the CCU is on the economy setting.

There are lots of posts (especially on the diesel forum) on how to check and if necessary replace the monovalve. It is easy to find on the firewall, on the RHS of the engine compartment. (referring to the RHS when sitting in the vehicle facing forwards). If the diaphragm on the monovalve is torn or the electrical plug is loose then heated water will be released into the heater core at all settings .....

If the monovalve is OK then you may have an AC clutch problem or a CCU issue.