Found this in the manual if it helps
If,after switching on the ignition,all symbols in the display area flash for about 15 seconds,there is a fault with the system-contact a vw dealer
* should the cooling system not work at anytime,either:
--the ambient temperature is less than approx. +5 *c
--the compressor of the cooling system has switched off temporarily due to the coolant temperature being to high
--or the fuses have blown
check fuse and,if necessary,renew it.If the trouble is not due to a defective fuse,have the climatronic checked.
*If the cooling system drops off,switch the a/c off and have the system checked