Product review (2 stars): Unit works but the dimensions of the foam are not correct and it has to be cut to size.
In order to install this, you have to very carefully trim about 1/4 inch of foam, specifically the portion that sits flat against the refrigerator wall.  I successfully did this using a serrated knife.  Without that problem, this is a very simple replacement taking about 15 to 20 minutes.  If they built this with the proper dimensions to directly replace the original, I would give it a 5 star.  Had I read the other reviews first and knew this problem, I would not have bought this; I want a direct fitting proper replacement.
Our refrigerator is a Kenmore Elite model 106.52603100.
As an additional note, last time this happened I had learned how to test the diffuser in a test mode from the front panel allowing you to push a sequence of buttons that will open and close the unit, but could not find the instructions anywhere this time around.  If you are trying to troubleshoot a similar problem, perhaps the manufacturer support people will tell you how to do it.  It makes the troubleshooting MUCH easier.