2004 Dodge Dakota A/C fan switch works only on the highest

What could be wrong? When turning on the Air conditioning, the fan switch needs to be set to its highest level for it to start blowing cold air. If turned one notch lower, it cuts the blower off and the cold air too.

I think its the fan switch thats defective. If I am wrong, could you give me diagnosis or what it could be before I take it in for fixing.

Thanks