I am doing an external heat simulation with a heatsink fan and a led volume source.

I am having trouble with the surface plot. When I don't involve the fans the surface plot looks normal with a gradient over the entire surface however when I add the fans to the simulation, suddenly the surface plot is the same temperature all over.

Is it not possible to have a surface plot at the same time as doing simulations with air flow?

My first thought was that the air cooled the solid enough but the heat source should definitely be much warmer than the heatsink. So I can't figure out what is wrong with the simulation.