Climate control.... Fahrenheit to Celsius

[95-J30tt]

well i have 3 climate control units sitting infront of me right now, first one is the original (came installed in the car, has a light problem, the green display lights dont come on, they are not burnt)

the second one i got from ebay.... when i turn on the interior lights (the green display lights), the screen dims, no matter what i do (the dimmer knob has a click at one end, which brightens up the stereo and the climate control screens... however, the CC that i got from ebay doesnt get brighter)

the third one, i went to a junk yard, and i pulled it off a 1993 canadian J30 (i took the unit out myself to make sure that it is of a canadian car), even then, when i connected it, it showed me Fehrenheit and not Celsius, can anyone explain that, is there a way i can change the display to Celsius and back ????, moreover, the screen doesnt brighten up either

i'm going to put back my original climate control back tonight to verify that there is nothing wrong with the connections

Any help is greatly appreciated