Need to replace my fridge defrost timer

[blood63]

I have a Kenmore refridgerator model 596.66039600. This has a bottom mount freezer.
After much research I am convinced that my defrost timer needs to be replaced. The trouble is I can't find it. This fridge being less than 5 years old, perhaps its does't have one.
Is it possible it is hidden somewhere in a secret compartment?
Is it possible that it doesn't have a defrost timer and some other parts are doing the same job?

[gotpasswords]

It's probably incorporated into the main control board, a roughly $110 part on this model.

Sears knows about pretty much every appliance model in North America. Needless to say, they have parts and info for their own products. If you haven't done so already, head over to www.searspartsdirect.com and plug in your fridge's model number to get exploded diagrams of its parts. During the day, you can also talk to them on the phone or chat online.

Also, if you look inside the fridge's backside, there's probably a schematic diagram of the thermostats, fans, defrost heater, etc. that will help indicate what the defrost heater is connected to. It may be pasted inside the frame near the compressor or on the back access panel.