Hi,

This got so long that I am listing my questions first with more detail below.

1. Is 26 ohms (26 not K or M, but 26) resistance on a defrost heater acceptable?
2. How to test a new defrost timer that has no continuity between terminals?
3. Should a refrigerator not cool and freezer be cold with the defrost heater removed?

I am seeking help/advice/information for a 13 year old GE top freezer refrigerator that is not cooling properly. The first symptom we noticed was that the ice maker quit producing ice, then, before I had a chance to check the ice maker ice cream was soft, etc. and there was frost on the back wall of the freezer. I have an old generic repair manual that has served me very well for many repairs in the past, so I consulted the troubleshooting guide.

The fans (condenser and evaporator) both work, the compressor runs so the common diagnosis for no ice/frost/not cold appeared to be the defrost system, which has also been the case on many other refrigerators before. I replaced the defrost timer since this usually fixes non fan, non compressor (starter or overload) problems, it is easy and relatively inexpensive ($22). After the refrigerator ran for about 36 hours the original conditions still existed – not cold enough (about 45 degrees bottom and 20 degrees top), frost remained on the back wall of the freezer, and there was no ice (too warm).

I have removed the guts of the freezer, the back panel, and used a hair dryer to melt the ice away to test the defrost heater, etc. and need to check my results since the repair manual does not give many specifics. The resistance of the defrost heater is near zero on an LaLaLaLaog meter and 26 ohms on a digital. I can not find any indication of what the resistance should be. It is so low that I question that the part is good, but I found one site that says generically that 31 ohms is OK. Also, even without the defrost heater installed the freezer does not get any colder, so maybe it is OK.

I turned the refrigerator back on with the defrost heater (along with the back panel etc.) removed and expected that it would cool properly, but the freezer is still only at about 20 degrees. I tried to test the new defrost timer using the method in my book – terminal 1 should have continuity with two other terminals, turn to click, should have continuity with two terminals but one not the same. I did not get continuity with any of the three other terminals before or after manually turning the timer. The time appears to work since the refrigerator runs – is there something about the internals of defrost timers now that prevents the old test method from working?

Help, what else should I do or what am I missing??

Thanks,

Dave

1) Yes, 36 ohms can be okay. If you can find your fridge's schematic hidden away on it somewhere, it may tell you the resistance of the defrost heater.

2) Your new defrost timer is designed to replace the old timer with the same technology. As far as I can think, it should test out as expected. It does happen that the replacement part can be defective. I recommend you call the retailer who sold you the part and tell them you think it is bad, and ask them how to confirm it. I suspect they will tell you to test it in the way you already tried.

3) The defrost timer interrupts operation to run a defrost cycle. By removing the defrost timer completely, you would interrupt the defrost cycle. But removing the defrost heater should not affect it as far as I know.

Your original problem was overtemp and so if the defrost system is not at fault, you have to consider other possibilities. Simple ones include and overfilled freezer or fridge or leaking door seals letting in warm air.

Hi DIY Guy,

Thanks for the reply. Yes, I had already confirmed that there was not a door seal problem and neither the frig or the freezer appeared to be over filled. I did find a schematic last night (very unintuitive and hidden location) and it does indicate that the heater is OK at 25 ohms. I could not get the defrost thermostat to test as good, but I also am have not sure I was patient enough in getting it cold enough to close.

The local theory is now that the defrost timer motor or gears were causing it to hang up and not turn on the defrost cycle as needed causing the evaporator freeze up and air was not moving to cool things down. Then after I replace the defrost time it was still too frozen for the normal defrost cycle to melt it. I have read that it will take about a week for the ice to build back up to the point of choking the air flow off again, so then I will know then if the defrost thermostat is actually bad/open. I now know how to quickly get the icemaker and back panel out and back in again if I need to, and that part does not cost much if required.

I DO HAVE A NEW, MORE GENERAL QUESTION RELATIVE TO THE ICE I FOUND ON THE EVAPORATOR, – My evaporator coil is two rows of coiled tube hanging horizontally at the back of the freezer. It is frosting up on the first 3/4th of the bottom coil with no build up on the remainder of the coils – is that a normal or expected frost/ice pattern, or should it be more evenly distributed???

Thanks again,

Dave

Ice on the coils suggests that the refrigerant pressure is too low. The result, aside from the ice, is a freezer and fridge that don't get cool enough.