hmm.... i used to know, but i forgot. Pull the CC panel out and look for a jumper on the board. Or check to see if there is a fuse to pull to change it to C.
To change the display to read metric, you have to connect one of the wires on the back of the ECC to ground. It's supposed to be a red wire, connected to pin 8 on the ECC. Actually, on some ECCs, there's no wire at all, but if you ground a pin 8, then the display changes to metric. The pin numbers in the ECC plastic housing are very tiny and hard to read; make sure you get the right one.