Ticking noise coming from left center vent when heat and A/C is in use.

What is your question?

I have a 2000 Lincoln LS V8 and when I use the A/C or heat there is a fast ticking sound coming from the center left vent. Everything functions properly, but the frequency of the sound increases as the level increases. On full blast it ticks every half second and slows down as I back it down. It's not coming from the engine just from that vent in the dash.

What makes this problem better or worse?

Only happens when heat or a/c is engaged

How long has your 2000 Lincoln LS had this problem?

One week