2004 Heating noise

When The automatic climate control switches from defrost to heat (Lower ducts) I hear a chattering sound from the dash. Also hear when in heat mode only with fan on high. Does this sound like a big job for the dealer to fix. I am not comfortable with having them disassemble my whole dash. Need the car and dont want it out of comission for a long time. Any thoughts would be appreciated.

Thanks

It must be on warranty. Take it back and demand a courtesy car. They have to give you one.