I have a GE side-by-side refrigerator that has started to not cool. The model # is (TFS22PPDA BS). I have tried defrosting it manuelly (removing all shelves, removing back pannel, clearing all ice off coils with blow dryer). But it only works for 3-4 days then the frost is back and the refrigerator is warm again. How do I know if it is the defrost timer,or heater or mother board? How hard it it to repair this problem?
Thanks BM

The defrost timer or heater switch went. That needs replacing. If yyou have no idea how to do this hire a repairdude. If you have a multitester you could test for yourself and see if that part is bad. If it is the motherboard - you'll need a new one.

Any idea how much will it cost to replace the defrost timer or heat switch or get this fixed?

I am having the same problem.Is there anyway of telling if the heater is bad just by looking at it?

If you can find the defrost timer, it will probably be about 2" square, probably be black, have 2 mounting screws, have 2 to 4 small wires. It will have a hole in the center with a screwdriver slot in it. The screw driver slot will be such that you can only turn it one way, clockwise. Insert a screwdriver and turn that shaft a slightly, you should feel a clicking. Turn 3-5 clicks. Wait to see if any defrosting occurs.

Defrost timer are relatively inexpensive ($20-35). Replacement is simple as you will see when you find it. Might be best to just replace it to be sure. Can be found at most appliance parts stores.

No you can not tell if a heater is bad by just looking at it. More likely timer than heater itself.

I usually turn the defrost timer until I hear it click into the defrost cycle. If you go around more than once you can soon identify the spot. I verify the heater by watching the amp draw with my DVM. If the amps drop to nothing but the cabinet light draw (compressor will be off course), then I suspect the heater or defrost thermostat. If it defrosts, then I visually check the defrost timer 'screw head' position and come back next day (with a new timer :D ) and check again. If it hasn't moved but the fridge has been running then the timer is shot (unless it has been running exactly 10 hours or whatever the defrost interval is, unlikely, but then the coils will be just defrosted too). Obviously I am not a dealer repairman, but it works for us.