1940 Philco refrigerator

able annie

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After 78 years, the fridge stopped working! All the wiring had insulation cracks with bare wire showing. We replaced the power cord and the three conductors from the compressor to the relay. The relay was a CR1057 General Electric. The relay tested no continuity between terminals 3 and 1. We turned it upside down and no change. So we replaced it with a Supco R041 relay. The wiring to the thermostat and light is very suspect, but inaccessible so far... To test the relay we disconnected all three wires for the thermostat and light, and put a temporary switch from the neutral side of the power cord to one of the power leads on the relay. The compressor comes on and runs drawing 188 watts and the relay gets very hot within 30 seconds. Interestingly, we moved the switch to the hot side of the power cord and the other power lead of the relay (no other changes) and the compressor runs and draws 335 watts. Again the relay got extremely hot quickly. Obviously we have work to do on the thermostat and light, but are hoping to solve this relay issue first.

1940 Philco Model C 885, Style RA, Serial 8AD111915
1/8 hp split phase motor, 2.8 amp
 

Dan O.

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So we replaced it with a Supco R041 relay.
1/8 hp split phase motor
The relay you installed is for a 1/4 HP compressor and the compressor in there appears to be an 1/8 HP. A more appropriate universal relay would have been a RO81.

But in either case those solid state relays do get hot. Clip it onto a nearby piece of metal to act as a heat sink.

We turned it upside down and no change.
Older refrigerators often used a 'hot wire' replay which are not normally affected by directional orientation and it would not affect any measurements. I have no idea what type of relay your original is.


runs drawing 188 watts and the relay gets very hot within 30 seconds. Interestingly, we moved the switch to the hot side of the power cord and the other power lead of the relay (no other changes) and the compressor runs and draws 335 watts.
i have no idea how you're getting different reading. Just a note, the hot side of a circuit should always be the one that is switched, for safety.

Dan O.
 

rickgburton

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Hi able annie, I found your thread.
able annie said:
....but relay gets very hot in 30 seconds..... Is there a difference if that lead is connected to L1 or N?
The relay will get hot. It doesn't matter which wire you connect to L1 and N. In those days the plug only had two terminals and they were both the same size so orienting it wasn't an issue. Dan is correct, RO81 is the correct relay for that size compressor if your compressor doesn't use a start capacitor.
 

able annie

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The compressor does not use a start capacitor. It is split phase. We replaced the wiring from the thermostat to the R081 relay (we've tried both R041 and R081, both ran hot...) Compressor started and ran normally. Fridge got cold. Relay got very hot and watts were 186. Then we tried replacing the R081 relay with the original relay CR1057 General Electric and it still worked! Stayed cool, watts 326. What accounts for the different wattage and what should it be? Happy the fridge is running!
 

rickgburton

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In all my years doing refrigerator repairs, not once did I need to check the watts. Watts is a unit of measurement on how much energy is being used. A 100 watt light bulb is going to use more energy than a 50 watt bulb and an older 1/8 hp compressor is going to use more energy than say a 1/16 hp compressor. A watt meter is good for checking how much energy it uses but that's about it. It does little good as a diagnostic tool.

The machine used a "hot wire" relay. A hot wire relay doesn't use an overload. Instead it uses a wire that's sensitive to current change. The compressor uses both the start and run windings to start the compressor. The bi-metal in the relay gets hot and warps, opening the connection between the start windings and run windings so the compressor is running on just the run windings. The solid state relay does basically the same thing only it uses a circuit board inside it.
 

able annie

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Hi Rick and Dan

I thank you both for your expertise

This fridge stopped running and we are sorting out several issues to get it up and running again. Concerning just the motor/compressor, (previously I gave wattage measurement but can easily think amps). I don't know what the expected draw is. The spec info on the fridge states 2.8 amps. Is that the expected running draw or a max at start up with maybe the light on? Or stated another way - if the motor is healthy what draw would you expect while running?

Thanks again - Annie
 

rickgburton

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2.8 sounds about right. At startup you can get a momentary high amp draw as much as 15-20 amps. Do you have the relay connected to the correct compressor terminals?
 
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