4 Wheel Drive/SUVs: 2003 Ford Expedition EB 5.4L, ford expedition, little spring

Question
I noticed yesterday after work there was a ticking noise coming from inside the cabin.  It only ticked 4-5 times, so I thought it was the radio.  When I started the truck up this morning, I heard the tick again, it is coming from where the return air is in the back of the cabin.  Very loud, constant as if contacts are not opening/closing properly and ticked the 1 hour to work.  I turned on the AC, it works, but did not have the rear on.  How do I get the panel off to check it?  Has anyone experienced this before?  

Thanks

Answer
Pulling those panels is abit o a pain but you can do it. Around the door opening pull the weatherstripping away from the truck frame and remove any obstructions if the panels. Gently but forcefully pull the panels toward the inside of the truck and they will pop loose. It is just little spring clips holding it on. This will expose the a/c unit for testing. sounds like a diverter door actuator position sensor not registering right

Matt