I noticed that there was frost building up on my freezer wall causing the freezer to not cool properly. I am able to turn it off and let it melt by itself and then restart it and then it works ok for a week. Then frost builds up again. I think the problem is with the defrost timer or thermostat. When the frost is built up on the freezer wall, I advance the defrost timer manually into the defrost mode. The refrigerator turns off. However the frost doesn't melt. I'm wondering if the reason the frost doesn't melt when I do this is because there is so much frost built up and the defrost heater doesn't have a chance to melt it in the 20 or so minutes. The reason I'm wondering this is because if I first let it melt by itself by turning off the refrigerator and then turn it back on and manually turn the defrost timer into defrost mode, I seems to be defrosting because I notice it warmer on the freezer wall. This leads me to beleive that maybe the thermostat is working but the defrost heater isn't having a chance to defrost because so much frost is there. Or should it melt the frost no what how much is there? I was wondering what you think. Thanks for your help.

Thanks Gene for your assistance. I took a look at your links. When I turn the defrost timer into defrost mode, I do hear the sizzling noise in the back. It sounds like water running and popping sometimes. However even though it seems the defrost heater is working, there is no melting of the frost. Is it because so much frost has built up and it can't be melted in one 20 minute cycle. If I try to let it melt on its own by turning off the power for 45 minutes, most of the frost melts but there is a little left. When I turn it back on, and put it into defrost mode, I can then see it melting what's left. So my main question is, is the amount of frost built up not allowing it to fully defrost in the 20 minute cycle? What do you think? Thanks again.

Thanks again Gene. I'm thinking it may not be the defrost timer. It seems to be advancing by itself. I put a mark on it. After completely melting the freezer and then letting frost build up for maybe 3 hours the heater isn't able to melt the frost. They only way it melts it is if I try it 1 hour after turning the freezer on. It seems any frost build up in excess of what would form in an hour, the heater isn't able to melt. Is it normal for frost to build up on the coils so quickly after turning the refrigerator back on? Could there be something else going on? Thanks.

Thanks Gene. I had the back cover off yesterday, letting it melt. With a little bit of frost remaining, I put it into manual defrost and watched the rest melt as the heater went on. There did not appear to be any frost left. I let it sit for another hour and then put the back cover back on and turned it on. Within a few hours there was frost again. By the time the normal defrost cycle is ready to begin, it is not able to melt all the frost, I think there may even be ice on the bottom of the coils now, because it is hard when I press with my finger on the bottom part. The rest of the coils probably have frost but no ice. The back cover has a thin layer of frost, but I think it will build up by tommorow. What could be causing the frost to build up so fast as to not allow the heater to melt it? I thought maybe the door gasket was bad, but it seems to be in full contact with refrigerator. Thanks again.