my 02 plate disco only blows warm air through vents i replaced a/c fan did not help even on economy mode warm air i thought the heater was manual in this mode but wont cool down the air through vents in manual or auto mode

Economy mode means no compressor action so it's normal to not be cold but if it's warm all the time first make sure there is gas in the system

surely economy mode should blow cold supposing the a/c or temp control or whatever it is called has low gas in it

Economy mode is with the air con off, means your getting more mpg, therefore more economic, as sierraferry said, if you've no gas in the system, then it won't blow cold, may be a leak in the system, had to have two pipes changed on mine, lucky it was under warranty

As everyone has already said, the economy button switches the air-con off and removes the load of the compressor from the engine.
If as is suggested there might be no gas in the system then the air-con won't work, it might even cause some damage to the air-con compressor, although the dual pressure switch should prevent it. The refrigerant as it circulates through the system also contains a lubricant for the compressor.
In either case all you'll get in the way of cooling will be from the movement of air either re-circulated within the car or the outside air being drawn/allowed in.
The air-con fan in the front of the radiator is used to assist airflow through the condenser, it has nothing to do with the airflow into the car.
Like the others who have already commented, I too would advise that you get the air-con system pressure tested and if necessary repaired and re-pressurised.

okay thanks, old 300 tdi didnt have aircon got plenty cold air through it, td5 just a money pit time to get rid