This fridge came in with several problems. The worst of which was the cabinet being bent into a diamond shape, so that neither the freezer nor the fridge compartments would close properly. I hadn't seen this sort of damage before, so it took some thinking to come up with a way to fix it. In the end, an extended hydraulic ram (porta-power) was easily able to straighten the cabinet. Can't imagine how this amount of bending happened, but it must have been an exciting day for someone.
The defrost problem was with the defrost control. These fridges have a time and temperature based defrost control. The defrost cycle initiates after so many hours of compressor run time. Then, the defrost cycle ends once the evaporator warms up to a certain temperature. I tried my best to get the defrost timer motor working; however the plastic gears had shrunk over time. They no longer mesh properly, and for that reason there is no way to consider that control reliable.
I know that it is possible to install a "regular" defrost timer in these, however there were some concerns with this. The timers I have seen all have a minimum operating temperature rating of 32°F; meaning that they are not intended to be mounted inside the freezer compartment like the original GE timer. Another concern is loss of the temperature controlled defrost termination. General Electric engineered this to be a cost-effective design. If they thought it would be OK without the temperature sensing defrost control, they would have eliminated that cost from the design. Without engineering documents it's hard to say for sure, but I expect that there are several reasons for this. One would be the inconsistent nature of the hot gas defrost. The amount of heat available will vary considerably based on how long the system had been running before the defrost cycle started; ambient temperature, and other factors. For that reason, the time necessary to defrost will not be constant. Also, since the compressor is running in a loop with little restriction, the suction pressure returning to the inlet will be very high. This will put a lot of load on the compressor. I am sure that GE wanted to be sure that the defrost cycle was ended before the return gas temperature was too warm for the compressor, under these operating conditions.
If there was a happy medium to be found using a fixed defrost cycle time, they would have found it, I expect. But they went to the cost and development time to use a time and temperature based control.
Having said that, the solution I used to replace the existing defrost control emulates the same functionality. There is a timer monitoring compressor run time. After 12 hours, the timer will enter a defrost cycle. The end of the defrost cycle is controlled by a defrost termination thermostat located on the evaporator, in the same location as the original temperature sensing bulb from the original defrost control. The timer and the thermostat work together (with a relay) to accomplish the same functionality as the original control. In the video, I explain this and draw a simplified schematic for this system. I do realize that some people will consider this overkill and a waste of time; but as said previously I am only keeping the intent of the original design, as opposed to losing some functionality which the factory had included.
Sincerely,
David
The defrost problem was with the defrost control. These fridges have a time and temperature based defrost control. The defrost cycle initiates after so many hours of compressor run time. Then, the defrost cycle ends once the evaporator warms up to a certain temperature. I tried my best to get the defrost timer motor working; however the plastic gears had shrunk over time. They no longer mesh properly, and for that reason there is no way to consider that control reliable.
I know that it is possible to install a "regular" defrost timer in these, however there were some concerns with this. The timers I have seen all have a minimum operating temperature rating of 32°F; meaning that they are not intended to be mounted inside the freezer compartment like the original GE timer. Another concern is loss of the temperature controlled defrost termination. General Electric engineered this to be a cost-effective design. If they thought it would be OK without the temperature sensing defrost control, they would have eliminated that cost from the design. Without engineering documents it's hard to say for sure, but I expect that there are several reasons for this. One would be the inconsistent nature of the hot gas defrost. The amount of heat available will vary considerably based on how long the system had been running before the defrost cycle started; ambient temperature, and other factors. For that reason, the time necessary to defrost will not be constant. Also, since the compressor is running in a loop with little restriction, the suction pressure returning to the inlet will be very high. This will put a lot of load on the compressor. I am sure that GE wanted to be sure that the defrost cycle was ended before the return gas temperature was too warm for the compressor, under these operating conditions.
If there was a happy medium to be found using a fixed defrost cycle time, they would have found it, I expect. But they went to the cost and development time to use a time and temperature based control.
Having said that, the solution I used to replace the existing defrost control emulates the same functionality. There is a timer monitoring compressor run time. After 12 hours, the timer will enter a defrost cycle. The end of the defrost cycle is controlled by a defrost termination thermostat located on the evaporator, in the same location as the original temperature sensing bulb from the original defrost control. The timer and the thermostat work together (with a relay) to accomplish the same functionality as the original control. In the video, I explain this and draw a simplified schematic for this system. I do realize that some people will consider this overkill and a waste of time; but as said previously I am only keeping the intent of the original design, as opposed to losing some functionality which the factory had included.
Sincerely,
David