1937 kelvinator ice cream cabinet charge pressure?

rickgburton

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It depends on the temperature. Use a refrigerant temperature/pressure chart and charge it by head pressure. That system uses a pound of R-12. Don't use R134a refrigerant. Don’t cure the symptom and leave the cause. Recharging a refrigeration system may correct the condition of insufficient cooling, but it does not correct the original problem unless a cause is found. A properly working system does not lose refrigerant over time.
temp pressure.jpg
 

Orvilsoft

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Thanks for the reply. I realize that there should not be a leak.
I really don't know anything about refrigeration and don't understand what temperature is referred to in the chart.
I have a friend who works on car a/c systems but he is not sure what to charge the unit to.
A home a/c guy put a gauge on the compressor the other day and read 35psi but he also wasn't sure what it should be.
I guess that no refrigerant should leak down even after 81 years?
 

rickgburton

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A home a/c guy put a gauge on the compressor the other day and read 35psi
Hmm....that's not good. If the compressor is running at 35 psi on the low side that would indicate the compressor is not pumping (bad). The head pressure is the high side pressure/temp relationship. The first column on the left side of the chart is the temperatures. All the columns to the right of the temps are the different types of refrigerant. Find the ambient temperature on the left side of the chart (or in the center of the high side gauge). Then move to the right until you get to the R12 column. Charge the high side to the correct pressure then you'll know what the low side should be. Probably somewhere around 2-5 psi. Here's the deal; Automotive AC and central AC units are different animals and very forgiving where 5-10 psi is no big deal. On domestic refrigeration 1-2 psi can be the difference between cooling and not cooling.


I guess that no refrigerant should leak down even after 81 years?
Refrigerant doesn't evaporate or break down and it's in a sealed system so the answer would be no.
 

Orvilsoft

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Well, thermostat is dead. Relay works but the overload constantly cycles.
Static pressure at 40. Compressor won't run long enough to build high and low pressures.
Needles start to move on gauges. Current rating on tag shows 3.3 amps. Compressor
drawing 8 amps at startup. Guess that's what is tripping the overload. The overload is a flat
piece of copper that bends and breaks a contact. I'll be checking where the wires go to
the compressor for any short this weekend. Is an old compressor like this salvageable?
 

rickgburton

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