hey guys, my ED's air con light comes on when i press the button but no change in air temperature. does it need re-gassing? and how much would that be, can a regualar servicing fix that up?

Have a read of this:

http://www.fordmods.com/forums/documents.php?doc=9

As for regassing, when you turn the air-con on is there a noise under the bonnet and it stops when you turn the air-con off?

Lift the bonnet, check aircon belt is turning the compressor. Turn off the engine and locate the valve on the receiver/drier [the black metal cylinder] in front of the condensor. Undo the valve cap to reveal the valve [looks like a tyre valve], keeping your eyes well out of the way, use a screwdriver or pen to gently depress the valve stem. If gas whooshes out, you have a charged system and maybe a service/top up is all you need. If nothing or almost nothing happens you probably have a discharged system and they'll need to find the leak/s and correct them.
Theoretically, they're a closed system and can't "run out" of gas without a leak but it could be a tiny leak that's hard to find. A dye charge helps locate most leaks.
Cheers,
Paul