Ranco A30 wiring help | MonitorTop Refrigerator Forum

Grigg
5 Cubic Foot

Posts: 95

Ranco A30 wiring help Nov 22, 2021 16:45:30 GMT jake likes this

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Post by Grigg on Nov 22, 2021 16:45:30 GMT

I'm replacing a defective control on a Nelson ice cream dipping cabinet.
Old one is a Ranco A30-3777-00
New one is Ranco A30-377-70

I thought the part number was the same; although similar the two controls are slightly different. I believe the operating characteristics are quite similar thus I'd still like to use it, or give it a try.

Question is about the wiring terminals. Old one just two terminals, easy to figure out.
New one has a "signal circuit" thus 4 terminals, and I'm unclear from the instructions how to wire it, please see pictures.
I have been unable to find better instructions or a wiring diagram by searching the Ranco site or otherwise online.

In testing with a multimeter the top two "signal circuit" terminals, normally open, close when cold.
Bottom "compressor terminals" both old and new are closed when warm, no change when cold (thus replacing the old one) unsure what that means for the new one.
At this point I'm unsure if my testing was complete or useful. I didn't log temperatures rising or falling, just stuck the bulb in a cold freezer or at room temperature.

Thanks for any guidance,
Grigg

Last Edit: Nov 22, 2021 16:51:31 GMT by Grigg

ckfan
Administrator

Posts: 2,869

Ranco A30 wiring help Nov 22, 2021 23:23:15 GMT via mobile jake likes this

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Post by ckfan on Nov 22, 2021 23:23:15 GMT

So it sounds like the wires that went to the original thermostat just need to go to the “compressor” terminals on the new one. I would just try it and see. More than likely the sensing bulb didn’t get cold enough when you stuck it in the freezer to open up the thermostat. That or the operating characteristics of it are completely different and you’ll have some real “concrete”.

I have to keep telling myself that this is a healthy addiction!

It is all in the name of preserving and enjoying these wonderful machines.

jake
9 Cubic Foot

Posts: 392

Ranco A30 wiring help Nov 23, 2021 18:17:57 GMT via mobile Travis and ckfan like this

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Post by jake on Nov 23, 2021 18:17:57 GMT

Some freezers have a light that will either be on anytime the freezer is plugged in to let you know the freezer has power. Or, on some freezers, the light will come on to warn you that the inside of the freezer is above 32°F and your food is melting. This light is often called a "signal light". I would suspect that is what the signal terminals are for. I agree with ckfan, hook up the two wires you have to the compressor terminals on the new thermostat and ignore the signal terminals if you don't have a signal light on your freezer.

Grigg
5 Cubic Foot

Posts: 95

Ranco A30 wiring help Mar 10, 2022 21:46:54 GMT jake, ckfan, and 1 more like this

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Post by Grigg on Mar 10, 2022 21:46:54 GMT

I appreciate the replies.

An indicator light makes sense. As suggested I ignored the extra terminals and hooked the compressor wires up as before.
Also found/made a little tool to wind the capillary tube up into a tight little pig tail like the old one had.

Freezer has been running off and on as expected all day holding temp between -10F and 0F, great for ice cream storage, and it is adjustable to somewhat warmer for dipping.

It's been several years now that I bought the ice cream freezer surplus from a school. Cost $36 including the fuel to go fetch it, and now $20 for the controller. Hopefully it is in good shape otherwise and I can use it for at least as many years as it's been sitting around to this point, so far so good.

Thanks for the info and guidance.

Grigg