clicking sound under center of dash with engine off

[lightandvideo]

I started the engine on my 2003 earlier, and immediately heard a loud irregular clicking sound under the center of the dash, (sounded and felt like it was coming from behind the radio, or somewhere behind the radio)

I turned off the engine and the noise stopped, then turned on the ignition (without turning the motor on) and the noise started again without the engine running, so the engine was not the source of the noise.

It was not a regular pattern like the clicks I have heard with bad relays ( but I could be wrong about this), and almost sounded like a small broken belt, or broken fan blade flapping around randomly, so I made sure the radio and the AC/heater system were off, but the noise continued clicking away...

I also tuned the AC/heater system and radio on, and everything worked, and the noise continued clicking...

I turned the motor back on and checked under the hood and couldn't hear any noises coming from the engine, and everything seemed fine with the engine,

Then I left the motor running and looked up under the dash to try to see the source of the noise, but it suddenly stopped before I could see where it was coming from,

I then drove to run some errands, and after several stops the noise still has not returned, but I am planning to take off on a road trip tomorrow and am worried about leaving without figuring out what the problem was,

Does anyone know what this noise could be?
Should I be worried about driving it tomorrow?

Any advise or ideas would be greatly appreciated, thanks!

 

[lightandvideo]

Some background on the vehicle, it is a good condition 4.6l XLT with 95k miles,

I purchased it a couple months ago from the second owner, this is the first problem I have had with it, seems to be in good condition overall, thanks again for your input on this!

 

[kmh1596]

Do you have the electronic climate control? Change the temperature and see if it continues to happen. If so, I would guess it is your blend door actuator.

 

[mindgame]

+1 Blend door actuator

 

[lightandvideo]

Thanks so much for your advice!
I ended up taking the road trip, and the noise started again when we turned on the heater, so I think you are right about it being the blend door actuator, (it is definitely something in the heater/AC system)

One thing, I do not think I have the electronic climate control, the temperature and setting controls are on 2 dial/switches, similar to the ones on my 99 F150 work truck, so am not sure if this makes a difference?

Is there a trick to accessing this part, or any advice on how to best complete the repair myself?
Thanks again!