Subzero 690 - freezer evaporator ice accumulation

[maxc1]

Hi,
for the last few weeks, i have noticed that my unit fan was running all the time. After reading a number of online resources i have found that my evaporator is completely blocked with ice.
I used a hair dryer to defrost and was hoping the issue will be resolved. Unfortunately, it kept coming and every a week or two i had to defrost it.
finally got someone to look and was told to replace the door seal, which i did. After a couple weeks the issue came back or was still the same. 

I was told that the sensor might be damaged, or the board.

attached please find the pictures of before and after:

https://ibb.co/cdjPvk
https://ibb.co/jrqWak

Please help.

Thank you

[Hiroshi]

Manual Freezer Evaporator Defrost was incorporated into the electronic control to assist in servicing and diagnostics. To initiate manual freezer evaporator defrost, press and hold the ICE ON/OFF key for 5 seconds, then release the key. 

If the machine will manually defrost, but does not regulate defrost cycles automatically- it is the control board. (these control are pretty reliable!)

If the machine will not defrost manually- it is the heater or defrost terminator.

[maxc1]

Thanks a lot Hitoshi.

i did the manual defrosting and it will not defrost. Is there a way to know whether it is the heater or terminator?

 

also is there a way to fix it or only replacement will work?

 

 

[maxc1]

For some reasons my iPhone misspelled your name. Thank you Hiroshi 

[Hiroshi]

Yes, you can check them.  A mutli-meter continuity test on the "terminator" and an Ohm's resistance check on the heater element...