[shankar]

Freezer is at 5degF but the food section is at 50dgF. Opened the back panel of freezer. Fan works fine, no ice buildup on the coils. But the sides walls at the separator (where the freezer and food section meet) are always hot. The compressor switches on and off as usual.

What seems to be the problem and how can it be fixed?

[denman]

Often just the condenser coils under the fridge need cleaning.

Here is a good link.
http://www.applianceaid.com/refrigerator.html
See #18 and then #4

I clean mine by removing the kick plate and the rear cover.
I also remove the drip tray.
I then roll it to an open outside door.
Then use an air compressor to blow it out.
I have been told that a leaf blower also does a good job.

This may not be practical for you but thought I would mention it.