i have the following code:

'^XA^CI28^CWZ,E:TT0003M_.FNT^FS^XZ^XA^FWN^FO70,50^A0,30,25^FH^FD'.function_parse($name).'^FS^FO70,90^BY2^B3,,100^FD' . $product['value'] . '^FS^XZ';

function_parse($name):
    $str = str_replace('Θ','_CE_98',$str);
        $str = str_replace('Κ','_CE_9A',$str);
        $str = str_replace('Μ','_CE_9C',$str);
        $str = str_replace('Ν','_CE_9D',$str);
        $str = str_replace('Ξ','_CE_9E',$str);
        $str = str_replace('Ο','_CE_9F',$str);
        $str = str_replace('ρ','_CF_81',$str);
        $str = str_replace('ψ','_CF_88',$str);
        $str = str_replace('ό','_CF_8C',$str);
        $str = str_replace('Ό','_CE_8C',$str);
        $str = str_replace('ύ','_cf_8d',$str);
        $str = str_replace('Ύ','_ce_8e',$str);
        $str = str_replace('ώ','_cf_8e',$str);
        $str = str_replace('Ώ','_ce_8f',$str);
        $str = str_replace('Έ','_ce_88',$str);
        $str = str_replace('Ί','_ce_8a',$str);
        return $str;

I have problems with the above greek characters, and the replacement i have made, returns instead of chinese letters, a ? for each such letter. What should the replacement be for these fonts?

We use a gc420t zebra printer if it is of any help