my coils froze up 2 months ago. defrosted unit and restarted one day later. exactly 2 months later having same problem. I'm told that this unit has a defrost board, and that would most likely be the culprit. I"m sure the defrost heater is working, only because it has been fine for 2 months with no problem. Any advise would be greatly appreciated.. This is a french door style. what really makes me crazy is that it is just over two years old.

See the attachment for the tech sheet.

I am assuming that you checked that the evaporator coils are heavily frosted over. Just to be sure that it is not same symptoms, different cause.

As Simon said the control board is at the top of the list but you may also want to check the defrost thermostat.
I could not find it in the parts breakdown but it will be clipped to the evaporator coils.

If it is deformed/bulged replace it.
Check it with a meter.
When frozen it should be 0 ohms.
At room temperature it should be 56,000 ohms.