GE TFX20SA back wall of freezer freezing (snow like more than ice) we took the fridge apart about a month ago and blew out and let everything behind the back panel melt as it was frozen solid, it then worked fine for about 3 weeks then started freezing on the back freezer wall again, stuff is not staying as cold also. Fridge is about 10 years old. Is there a way to defrost it? Not the most skilled repair person on my own. thanks

CLICK HERE for an expanded view of your freezer section.

Can you see the evaporator fan moving when it is plugged in?

Otherwise your defrost timer has failed.
#257 in THIS diagram
CLICK HERE to see the part.
CLICK HERE for testimonials about installing the defrost timer yourself.

Thanks for using FixYa - a VERY HELPFUL rating is appreciated for answering your FREE question.

CHECK DEFROST TIMER, CHECK HEATING ELEMENTS @ EVAPORATOR. BUT SURE MUST BE THE DEFROST TIMER. TO CHECK TIMER, IF IS MANUAL U CAN USE A SCREW DRVER TO TURN IT, IF IT DOES NOT DEFROST IT`S THE TIMER. NOW IT IF TIMER IS A ELECTRONIC TYPE, THAT CAN`T BE TESTED MANUALLY. REPLACE IT TO PRENET ICEBUILD UP @ EVAPORATOR.

There can be three issues: defrost heater (part WR51X10101), defrost thermostat (part WR50X0122) or control unit (part WR09X0122).
Check the heater first, use the tester, it shoud measure '0' (resistance 26 Ohm - it was 'infinity' in my case, i.e. it it was the culprit). You can buy it from AP Wagner (http://www.apwagner.com/).
If that happens again, replace control unit, then try thermostat.

hope it helps.