My freezer is going from 0 degrees to 40 degrees and back to 0. Had a service man come out and look at and was told to replace the relay and capactior. Asked him several times if it could be the compressor he said no because is was cooling back off. Well now that its doing this again I am not sure what it could be. I am think it could be the defrost tstat but I do not know can someone please help me?

Gene here are the results on the test we did. We did all of the service test in the tech sheet and they were all normal. It seems like when it is going up and down in the temp that its kind of stuck in defrost mode. We can go for several days and the temp in the freezer is fine but then it starts going up like its defrosting for some reason. I know that the freezer is supose to go into a defrost mode at some point but stay in defrost as long as it does. Everything starts to melt. But once again it does not go over 40 degrees???? This is what makes us think it could be either the defrost timer or tstat or maybe even the heater. So anymore help that you have is very much appricated. Thanks