Changing color on pixel art

I am making a pac-man game with a personal twist. To make the game look better, I want the color of the map to change with time. This is the original map I made and imported into the scene.138953-what-i-have.png

The problem is that when I try to change the color of the map through either the sprite renderer or a material I create, almost every color ends up being black just like in this image where I set the color to red.138954-what-i-get.png

Is there a way to fix this issue easily or do I have to manually create and import 10 different sets of maps with a different color each time ? It doesn’t seem like the most efficient way to do this…

Create the original texture with white instead of blue where you want to change colours and then it should work.