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Question for Johnson A419 Users

My Ranco temp controller recently stopped working so I purchased a Johnson A419 for use on my Sam’s Club 7.0 cu. ft. GE chest freezer. I use the freezer for both lagering and as a kegerator. The Ranco worked fine with this freezer until the controller stopped working altogether. However, I can’t seem to get the Johnson controller to work (I have tried two Johnson controllers, with both, I experienced the same problem, so it’s either user error or the deep freeze).

I have extreme swings in temperature. I have the set point at 40F, but the temperature gets as low as at least 22F. It froze a glass of water I used as a test rather than adding the 15 gallons of kegged beer ready be chilled for drinking (I have another 15 gallons waiting to be kegged, cooled, carbed, and consumed, so I’m anxious to resolve this problem).

The controller settings are as follows: SP 40F, diF 2, ASd 5, OFS 0, SF 0. I have tried to change those settings and I have tried both “cooling cut-in” and “cooling cut-out” modes, with no change in the temperature swings. I have also tried the probe being suspended in air, wrapped in one t-shirt, wrapped in many layers of t-shirts, etc…

If anyone has any advice to get this set up working, please let me know. I have a lot of beer to carb, cool, and drink. This problem confuses me as I assume the controller cuts the main power at SP, which would prevent further cooling (eliminating the freezer as the problem). Worst case scenario, I buy a refrigerator and convert it into a proper kegerator, which, in the grand scheme of life, would be tolerable.

Thanks,
Hobbs

Have you tried inserting your probe into a glass of water? When the compressor runs, it will run longer, but it will run less frequently (as compared to letting it be suspended in air).

That said, I just let mine sit exposed in the air, but you will get stratification even then: your kegerator will be warmer (maybe only by a couple degrees) at the top, compared to the very bottom. Where does your probe sit?

You could also try to use / create / install a fan to encourage better air mixing and airflow.

Do you have some 5 gallon pail to put in the freezer to simulate beer? Then tape the temp probe to the side of the pail.

“The controller settings are as follows: SP 40F, diF 2, ASd 5, OFS 0, SF 0.”

BTW, based on my experience with my unit a sp of 40 plus the dif of 2 will result in a low temp of 36. If you don’t want it this low, change the dif to 1 which will result in a low of 38. In cooling mode spf of 40 is the temp that the until will allow the temps to get to before it turns the freezer back on, the low temp is when it cuts out.

I know it’s not what you were asking about, but i found this to be useful when i set mine up.

At work at the moment, so I can’t tell you my settings. But I keep my probe up against the side of my corny, covered with a piece of foam and held in place with a strap. The idea being that you want to measure the temperature of the keg’s contents and not just the air in the freezer.

You might also want to do a sanity test on the accuracy of your probe. Stick a fridge/freezer thermometer in there and see if that agrees with what the A419 is telling you.

Thank you all for your responses. I read about the probe-in-water trick, but was concerned about the water damaging the probe. It seems pretty common though, so I’ll give it a try. I will also adjust my dif to 1 and see if that helps.

I’m going to stick a 5-gallon pail with water in the freezer right now. I hadn’t thought of that. I wondered whether the fluctuations might be the result of the freezer being empty. The water in a pail idea should answer that question. I’ll attach the probe to the side as Takehiko suggests and see if that helps, as well.

Thank you for your input.

Hobbs.

I can see how the thermal mass of the five gallons of water will help keep temps more consistent, but i don’t see how it actually has an impact on the fact that the unit is allowing the freezer to continue to chill past the set temp. It should hit temp and then cut power.

It is either not cutting the power or the freezer continues to chill after power being cut. IDK, but i’m dying to find out why this is not working. FWIW, my controller works great.

[quote=“mppatriots”]I can see how the thermal mass of the five gallons of water will help keep temps more consistent, but i don’t see how it actually has an impact on the fact that the unit is allowing the freezer to continue to chill past the set temp. It should hit temp and then cut power.

It is either not cutting the power or the freezer continues to chill after power being cut. IDK, but i’m dying to find out why this is not working. FWIW, my controller works great.[/quote]

My sentiments, as well. I don’t mind undertaking the project of converting a fridge into a proper kegerator (if I can find a fridge at a decent price, I would actually look forward to it), but I can’t understand why the freezer keeps cooling. Last night I watched the temperature hit around 40F (set point) on the controller. The light on the front of the freezer turned off and the light on the controller itself turned off, implying that power was cut to the freezer. Despite power apparently being cut, the controller temperature read out continued to drop until it reached 27F. This has happened with three controllers now (one Ranco and two Johnson’s). It has to be some quirk with the freezer itself, although this set up worked fine for about a year of use.

Hobbs.

You didn’t mention if this last test involved more stuff in the freezer or not. When the freezer turns on the cooling coils in the walls of the freezer get cold, obviously. But when the power is cut the walls don’t instantly warm up. They are still cold and will continue to cool the contents of the freezer. This is where thermal mass inside the freezer will really come into play. The more “stuff” you have in there the more stable the temp will be. And these overshoots will become less dramatic the fuller the freezer is.

Was the appliance’s control turned all the way up? I remember when installing mine that being a critical thing for me as to allow the Johnson’s to regulate the temperature and nOt the appliance or in my case the two would have been sharing control.

[/quote]You didn’t mention if this last test involved more stuff in the freezer or not. When the freezer turns on the cooling coils in the walls of the freezer get cold, obviously. But when the power is cut the walls don’t instantly warm up. They are still cold and will continue to cool the contents of the freezer. This is where thermal mass inside the freezer will really come into play. The more “stuff” you have in there the more stable the temp will be. And these overshoots will become less dramatic the fuller the freezer is.[/quote]

I had 12 gallons of water in the freezer. I had the probe insulated and wedged between the two buckets of water.

Also, I had the freezer itself set at the coldest temp. Although, I have also had it at the middle setting during these tests, as well, without any noticeable difference.

Hobbs

The setting on the freezer thermostat doesn’t matter as long as it’s set to run, it’s just an on/off for the compressor and doesn’t cool faster if set to a colder setting. In other words, the compressor runs until it hits the thermostat set point then turns off.

Do you hear the compressor actually turn off when the controller cuts power? If not, you have a bad controller or a wiring problem. Stupid question, but making sure: controller is plugged into wall, freezer is plugged into controller?

I’ve seen a similar problem to yours with overshoot when I had the probe touching the sidewall of the freezer. I was reading the temp of the refrigerant not the actual air temp in the freezer. Yes, more mass will add stability as others have said. Insulating the probe from the sidewalls will help, taping to a full keg (and topping with bubble wrap) near the middle of the freezer will force the freezer to cool that whole keg to your specific set temp before shutting off, and it won’t cut on again until the whole keg gets above the set temp.

Hanging the probe in the air works fine for lots of people, it helps to hang it in the middle and to have kegs blocking the line of direct sight to the sidewalls. It could be that your freezer has a lot of stored cooling energy in the coils when the compressor shuts off, so it way overcools the box unless there is something in there with which to exchange heat. Even one full keg has enough thermal mass to prevent being overcooled by the coil overshoot, assuming the thing is actually cutting off as its supposed to.

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