I have already bought a new fridge because of information from local appliance techs. Would like to verify information I was given from them with techs on here.

I was noticing frost on the damper vent in my fridge and eventually my fridge becomes warm while my freezer is still working fine. I found that on this model you can go into diagnostic mode and manually turn on the defrost heater and the defrost heater works.

I was told that if the thermostat is bad the heater still would not come on even if forced it to in diagnostic mode. The tech came to the conclusion ( over the phone ) that this sounded like a control board issue. Control board was roughly 200 but on a 2 week minimum nation wide back order so I decided to buy a new fridge as I couldn't wait and didn't want to deal with constantly forcing it to defrost cause you have to leave the fridge door open otherwise it returns to normal operation after the door is closed and exits diagnostic mode.

If already ruled out the damper motor as the vent is open and I get air movement after I manually defrost. I removed the back panel in the freezer yesterday (fridge will arrive today) and obviously found a fully frosted over evap. Evap fan motor operating correctly as well.

Looking for any suggestions as id like to fix this for a garage fridge its obviously 11 years old and close to its expected life expectancy if not over it.