Loud Compressor - 1949 Westinghouse Refrigerator restored
I have recently restored a 1949 Westinghouse refrigerator that I received from a neighbour downsizing. They told me it worked last they had it running. There was no way to confirm this as when I got it the wires were torn from the compressor. So I continued with the restoration, finished, figured out the wiring of the compressor, plugged it in and boom, she fired right up. Within minutes the ice box was ice cold, walls of the refrigerator were cold, all good signs to someone who doesn't do this work for a living. Here's the problem, right from the get go the compressor running was loud, not a loud hum, not a low hum, just loud, no other way to describe it. So I continued to monitor its progress. Shot the temperature laser at back of fridge cover, was around 30 degrees celcius. I have a power meter that plugs into the wall and then the refrigerator plugged into it. I tells me the input voltage, amps, watts, etc. and everything seems to be within spec except maybe the amp draw. After about 20-30 min the compressor shuts off, but not off like it stops running more like the sound when an electric motor is trying to run but gets jammed, sort of a humming noise. I know my way around a tool box so I knew at this point best to unplug it. I tried it again the next day. Same thing.
Here's what common sense tells me. The compressor is wired correctly and starts to function as it should. There is at least some refrigerant in it as the freezer box and fridge walls get ice cold almost immediately. I did test the thermostat out simply by turning it to the off position and the compressor did shut off. It restarted when I turned thermo back to a cooling setting. This is a 1949 refrigerator, there is no condenser or evaporator or fans just the compressor with high pressure line running to the coils up the back of the fridge and the low pressure line to the thermostat. This low pressure line does get joined with another line from a small 3 inch cylindrical shape part attached at the base of the back cover and it to runs to the thermostat. Sort of looks like a filter. The back cover is also where high pressure line/coil run. I would post pics but am no allowed at this point. Here are the specs on the back of the fridge.
Refrigeration Unit Specs:
Refrigerant: 15ozs of F-12 (not R-12, F-12) Im assuming the F stands for Freon (which I know is a brand name)
200 Test Pressure
Here are the wiring resistance specs:
Start to common: 14.3 ohms
Start to run: 17.4 ohms
Common to run: 3.5 ohms
Specs from power meter:
Input voltage: 121v
Amps: 4.4 (not sure if this is OK since tag on back of fridge says 3 amps)
It also has peak wattage and lowest wattage but can't recall what they were
So to sum up, my question is, could the compressor be low on oil and is it OK to add oil thru a piercing valve method the same as you would if you needed refrigerant? This is my only hypothesis so please let me know of other possible reasons the compressor is so loud and then has the electric motor jam up (I think) inside after about 20 min or so. Please remember 1949 unit. Sorry for such a long post but I try and provide as much info as possible to avoid unnecessary correspondence back and forth about specs. Thanks in advance for any insight.