Thank you all for the reply and suggestions!

my sears kenmore model number is 106.53552201, it is a side by side
referigerator. it has an electronic control board. i can not find the
defrost timer. does anyone know where it is ?

It is the evaporter coil inside the freezer that is icing up, not the
condeser like i mentioned previously. i guess this restricts the air
flow to the referigerator side. strange, when i defrost the freezer,
eveything comes back to normal, but after about 3 months, it ices up
again.

i ordered the following parts to see if this helps.

2 THERMISTOR 1 for the referigerator and 1 for the freezer
1 bimetal defroster (defrost terminator)

i'll see what happens. sure hates to trash a 2.5 year old
referigerator.