My freezer works, makes ice, but fridge is warm. A contractor came out today and said it was my defroster and he could fix for $275 ($185 parts and $90 labor). That seemed pricey so I'm looking to fix myself. All the posts about this topic seem to say it's the defrost timer but I can't seem to find it in the diagram. What was my contractor referencing? Do I need a defrost timer, defrost thermostat and defrost heater? Any help in telling me what parts I need is appreciated.

Okay - i pulled the panel off and i see the heater. It basically looks like a long thin light bulb but it seems okay (no cracks, not blown open)

Thanks for the reply - I appreciate it. And yes, how nice of my fridge to need that expensive part. So would there be anything else to check before buying the mother board?
I mean, would the 9 inch double glass tube heater only stop working if it was cracked? The parts diagram shows the price as $31 (not bad) and it says the redesigned heater kit now uses two heating elements to give a better defrost cycle. It replaces the single element that was used on some models - is it worth it to replace this? Could my problem be a thermostat? I guess I am asking if I have explored all other options before purchasing the defrost timer/mother board.

yours may be the older style single heater, it has been replaced with a double heater, i use my meter to confirm heater is good , discouleration is normal after years of use, failure of the single heater is common