Dash Noise

I have an RX 300 (2000 65,000 miles) and lately I hear clicking noises emanating from the dashboard intermittently. I removed the CD cassette from the changer, changed all the air conditioning settings and still hear the noise. It sounds like a relay opening and closing and it sounds like it is comming from the top center of the dash. Does anyone have any ideas what this might be and what it takes to fix it?