Any refrig/freezer techs here? Coils icing over.

[Cheetah]

Hey gang, is anyone here a refrigerator/freezer technician? I've been troubleshooting my freezer coils icing over, but so far have had no good success.

GE model HSS25IFMDWW

The coils in the back of the freezer were completely frozen back in the end of June. I defrosted the whole thing, replaced the defrost thermostat, and it all cooled down great. I skipped replacing the defrost heater ($55) and the system motherboard ($170) due to cost of parts. There is no defrost timer on this unit, it is all controlled electronically by the motherboard.

Now 3-4 weeks later the coils are all frozen up again. Most ice at the top, bottom of the coils are not entirely frost free but not nearly as bad as the top. I tested resistance on the defrost heater and it seems to be OK. I am going to try running a bit as-is to see if the heater will turn on so I can see it working.

I read some info online suggesting that if the top of the coils are frozen but not the bottoms then the defrost system is probably fine, and it is an issue with the coils or something that requires a technician... I'm not really interested in paying a tech to come out if I can avoid it.

So... Anyone here have any good ideas to try that doesn't involve manually thawing it all out every month, or buying a whole new fridge?

thanks.

[papabear]

Those heaters may be intermitten in my experience. The coil inside looks good and tests good but doesnt have good connection to terminal. If you go to board and unplug heater harness you can test the whole thing, tstat and heater, at the plug. While it is unplugged jumper it and then plug in. If it is good, heater coil will glow red hot in a few minutes. I have replaced a lot of these coils that test good then bad then good again. Be careful and good luck.

[Cheetah]

Thanks for the suggestion. The defrost heater never did turn on after my test the other day. I ordered the motherboard for just under $100 via Amazon. I read some comments online indicating the GE boards were prone to issues. If the board doesn't fix it, the defrost heater is next...