I have a Samsung model RB2155SW/XAA, and the unit works perfectly for about 12-16 hours from a fresh start, untill the 1st defrost, and then it does not recycle after the defrost. If I were to put it on a 6-hour wall timer, or unplug it and replug mannualy every so often, the unit would work perfectly. I have already replced the PBA Main Board and both upper and lower defrost sensors and themal fuses. The heaters check out fine, but again the unit will not come out of first defrost cycle and eventually both the upper an dlower get warm. Any help would be appreciated.

David