Most of the defrost heaters on the older are on the floor so to speak of the freezer, if you open the frig & see a drop hump in the ceiling that is where it is. PATIENCE is the key word for working on one. This was built by Admiral & was a lot of fun to work on. Might try a NT19 model under Admiral to get an idea, not easy to work on as to access the heaters etc. you have to remove both the refrig & freezer doors,center divide strip, then you can pull the bottom of the freezer out. I did Maytag & Admiral warranty for 15-20 years & got use to it.