It emulates a teletype by default, so sends a carriage return (ASCII code 0x0d or '\r') when you press the Enter key. Keyboards don't have a linefeed key anymore like teletypes used to have so you have to press Ctrl+J to generate a linefeed (ASCII code 0x0a or '\n').
Keep the normal sequence in mind, carriage return is first, "\r\n". You might want to tweak your code if you now use send("C\n\r").
It's been too long since I tinkered with it but iirc it had config to tell it to send a linefeed or a cr+lf when you press Enter.