How do I fix my broken heater fan switch that's in the car on my 2004 Kia Rio?

I had the same problem. Mine was loose, If you can push on it to make it work then yours is loose too. Remove the cluster with all the cables and wiring harnesses. Take

a close look at it from behind and push on it and you will see where it is loose. Take

a clamp like a C clamp and clamp it tight and mix up some epoxy and cement that sucker from coming loose. If yours doesn't seem to have this exact problem then order just the fan switch from Kia. You don't have to buy the whole cluster from what a friend of mine told me. The part isn't to bad, I think it was under 25 bucks.