I have a 1998 C230 and I must have accidentally turned Economy mode on and my AC doesnt work. As dumb as it sounds I don't know how to turn it off, pressing the EC button doesnt turn it off any one know how to turn it off?

 

Try putting it back in automatic.

 

Not sure whether this helps, but...

I've just bought a 1998 C200 and, when I test drove it, the EC button, rear windscreen demister and internal air circulation buttons all worked, but the heater was on hot constantly and the blowers weren't working.
The dealer said the latter faults were down to a blown fuse and he'd ensure they were fixed when I picked the car up.
However, when I did collect the car, the heater and blowers were still broken, along with the EC function, internal air circulation option and internal movement sensor / anti tow function(strangely, the other buttons on the console: rear windscreen demister, manual door lock / unlock button and rear windscreen wiper / washer are all still working properly).
As it was under warranty, I could get it checked at no cost to me and it turns out the entire unit behind the console had packed in and needs replacing.
It may be worth you having the unit checked out as it may be that yours is on it's way out as well.

 

If the "EC" light is constantly on, it is because the is a fault/code in the a/c pushbutton. The only way to turn it off is to erase the code.