Recently my Whirlpool refrigerator (model number ISC23CNEXY02) has started making a clacking noise every 4 seconds. It will clack every 4 seconds for an hour, then make no noise for 5-6 hours, then start clacking again. It is loud enough to wake me up in a bed about 60 feet away.
Looking inside the fridge, the noise is coming from the top left inside of the refrigerator compartment. There's a rectangular plastic piece, maybe 3 inches by 1.5 inches, attached to a spring. It tries to lower from vertical toward the refrigerator, then something causes it to spring back up to vertical which makes the noise.
As near as I can tell, this part is the diffuser/air damper (click through to "Refrigerator Liner Parts", part number 4).
I am wondering if there is a piece of (ice, something else) that's stuck and causing it to not close fully. However I'm having trouble getting the plastic off to actually look at it more closely. I don't want to damage it but there are no visible screws and I can't tell how to get the cover off.
Other assorted Googling suggests the diffuser motor may be going bad. The refrigerator is six years old (conveniently, just out of the warranty period.)
Can you help me diagnose the issue? I'm fine ordering a new part and asking someone to come out to install it. But I am going to feel silly if I do that and it turns out the problem is ice in the diffuser or something.