Thanks to networking with fellow enthusiasts, this fridge made its way across the state of Alabama to my shop for repairs!
The failure narrative is fairly simple. The fridge was plugged in and working, but the wiring was deemed too unsafe to leave it running. It was powered off and stored for about 7 years. In preparation of rewiring it, it was started up for a test run, and found to "run but doesn't cool." It was taken to a local shop who looked at it but was unable to troubleshoot it. The fridge came here with the relay removed and damaged, and missing the relay bracket. Got to love how some people treat others' property, don't you!!!
This one is a special one; because it's got a porcelain enamel cabinet, in a "1" size. GE had a "1" and a "2" size, as well as larger models. The "1" is a lower cost apartment-size cabinet. The "2" is the more common household size fridge. The reason a porcelain coated "1" size is uncommon is because that cabinet cost more than a painted full-size "2" model. Most people who were cost-conscious would prefer a larger cabinet (painted instead of porcelain) for their money. They didn't sell many of these.
The cabinet light will be rewired, and the gaskets all replaced as well, before it goes back home.
On to the repairs!
There are really three likely causes of a runs but doesn't cool issue; with a CK. Either there is no refrigerant; the float isn't allowing the refrigerant to flow; or the compressor unloader is not closing and allowing the compressor to build pressure.
In this case, I was able to determine the problem was a blockage or failure in the float. This was determined by cracking open the service port with the Bristol key from the hermetic service kit. After the compressor had been run for 10 or 15 minutes, the port was cracked open slightly. There was liquid SO2 present at the port, which escaped immediately when the port was cracked open. The port is on top of the float chamber, so that confirms the chamber was full of liquid, but the float valve was not opening. I tried the usual tapping on the float valve stem, and heating it gently with a heat gun. Nothing worked and no flow was established.
After determining the problem was in the float, the next step was to remove the SO2 and open the system. After ensuring the SO2 was disposed of, I cut the line below the float valve outlet (where liquid refrigerant goes to the evaporator.) Even after hours of sitting, the evaporator and compressor housing were still under vacuum. The bad float had prevented any refrigerant from reaching the evaporator. The compressor had pumped all the refrigerant into the high side, leaving the low side in a vacuum.
After finding this, I hooked up a nitrogen hose to the cut line, and let the compressor pump nitrogen to purge out more residual SO2. This also proved the compressor unloader is working and the compressor is functional.
Knowing what we had to work with, I proceeded to convert it to capillary tube metering. This will eliminate the entire float system from the machine. Thanks to another enthusiast, the homework has been done already, to calculate and test the correct size capillary tube for a 1/8 HP GE Scotch Yoke machine using R152A. I was able to proceed with the conversion without worry that the cap tube might not be the correct length or size. The capillary tube he determined is a 0.031" inner diameter, with 120 inch length. This happens to be one entire pack of Supco BC-1 capillary tube. Don't forget to score and break the ends, because the tube comes in the package with the ends sheared and crushed. Thinking of using the entire pack or tube, I almost made that mistake.
Wanting to make a "hidden" conversion, I decided to use the shell of the float chamber as the bracket to support everything. I used the plasma torch to cut away as much of the float chamber as necessary to remove the float mechanism and allow room to work inside.
I also modified the proprietary service port, so that a more common Schrader port is hidden inside it, concealed by the original cap.
The entire capillary tube conversion is concealed inside the insulation space.
The video has many details!
Hope this is interesting! Sincerely,
David
The failure narrative is fairly simple. The fridge was plugged in and working, but the wiring was deemed too unsafe to leave it running. It was powered off and stored for about 7 years. In preparation of rewiring it, it was started up for a test run, and found to "run but doesn't cool." It was taken to a local shop who looked at it but was unable to troubleshoot it. The fridge came here with the relay removed and damaged, and missing the relay bracket. Got to love how some people treat others' property, don't you!!!
This one is a special one; because it's got a porcelain enamel cabinet, in a "1" size. GE had a "1" and a "2" size, as well as larger models. The "1" is a lower cost apartment-size cabinet. The "2" is the more common household size fridge. The reason a porcelain coated "1" size is uncommon is because that cabinet cost more than a painted full-size "2" model. Most people who were cost-conscious would prefer a larger cabinet (painted instead of porcelain) for their money. They didn't sell many of these.
The cabinet light will be rewired, and the gaskets all replaced as well, before it goes back home.
On to the repairs!
There are really three likely causes of a runs but doesn't cool issue; with a CK. Either there is no refrigerant; the float isn't allowing the refrigerant to flow; or the compressor unloader is not closing and allowing the compressor to build pressure.
In this case, I was able to determine the problem was a blockage or failure in the float. This was determined by cracking open the service port with the Bristol key from the hermetic service kit. After the compressor had been run for 10 or 15 minutes, the port was cracked open slightly. There was liquid SO2 present at the port, which escaped immediately when the port was cracked open. The port is on top of the float chamber, so that confirms the chamber was full of liquid, but the float valve was not opening. I tried the usual tapping on the float valve stem, and heating it gently with a heat gun. Nothing worked and no flow was established.
After determining the problem was in the float, the next step was to remove the SO2 and open the system. After ensuring the SO2 was disposed of, I cut the line below the float valve outlet (where liquid refrigerant goes to the evaporator.) Even after hours of sitting, the evaporator and compressor housing were still under vacuum. The bad float had prevented any refrigerant from reaching the evaporator. The compressor had pumped all the refrigerant into the high side, leaving the low side in a vacuum.
After finding this, I hooked up a nitrogen hose to the cut line, and let the compressor pump nitrogen to purge out more residual SO2. This also proved the compressor unloader is working and the compressor is functional.
Knowing what we had to work with, I proceeded to convert it to capillary tube metering. This will eliminate the entire float system from the machine. Thanks to another enthusiast, the homework has been done already, to calculate and test the correct size capillary tube for a 1/8 HP GE Scotch Yoke machine using R152A. I was able to proceed with the conversion without worry that the cap tube might not be the correct length or size. The capillary tube he determined is a 0.031" inner diameter, with 120 inch length. This happens to be one entire pack of Supco BC-1 capillary tube. Don't forget to score and break the ends, because the tube comes in the package with the ends sheared and crushed. Thinking of using the entire pack or tube, I almost made that mistake.
Wanting to make a "hidden" conversion, I decided to use the shell of the float chamber as the bracket to support everything. I used the plasma torch to cut away as much of the float chamber as necessary to remove the float mechanism and allow room to work inside.
I also modified the proprietary service port, so that a more common Schrader port is hidden inside it, concealed by the original cap.
The entire capillary tube conversion is concealed inside the insulation space.
The video has many details!
Hope this is interesting! Sincerely,
David
