climate control, led installation troubleshoot Options

[poix]

my friend and i tried to install led lights on his climate control. we switched the stock led orange lights to white leds. but the white led won't light up when he turn the lights on, is it because the led doesnt dim (when the lights are on, the stock led lights dims)?

also we have trouble installing the 5mm leds to switch the light bulbs with sockets. i know it'll be easier to use a 3mm led but we dont know where to get the 3mm ones. also we dont know where the positives and negatives are to replace the socket ones. can some one tell me how to install with the 5mm?? or where can i get 3mm leds??