[cmargeson]

Hey Everyone,

I've gotten a big old Kenmore chest freezer from a guy in my homebrew club, that I'd like to use as a fermentation and lagering chamber.  Works fine, just old.  I also have a Johnson analog single-knob external thermostat.  The external thermostat/freezer are plugged into an extension cord, which is also plugged into a voltage/wattage meter (I'd like to know how much running this ancient leviathan will cost me).

https://imgur.com/tuPt2Yn
https://imgur.com/6KQn5a7
https://imgur.com/lANhij2
https://imgur.com/jJVx2oB
https://imgur.com/JRuCX34
https://imgur.com/4h0kXjy
https://imgur.com/nhY1ykk
https://imgur.com/v6C64MA

I've tried running it at 50 degrees, but it'll get it down to temp once then, pfft, won't cycle, and gradually get warmer.  If I start the freezer off cold, then let it rise, same story.  But when I remove the external thermostat and just plug it in, runs and cycles fine.

When I twist the knob on the thermostat, the freezer will start to cycle, stop, start, then finally quit.  Again, take away the thermostat, works fine.  Any ideas what is going on here?

Update 5/20/2020

Problem solved!  It took a week of careful watching, but the ancient freezer now holds temp steady at 50 degrees.  As it turned out, it was a three-part problem:

1. @KellerBrauer was right (so were others), the standard 14 gauge extension cord I was using had too much amperage drop-off; by moving the entire freezer over to the outlet, the freezer would cycle normally.  That thermostat though. . . .

2. @a10t2 - The thermostat WAS working, but it was way off calibration.  I spent a few days playing around with temp settings, and found that if I set it for 46 degrees, it would cycle the freezer and hold the temp at 50 degrees.

3. @TeeDubb - It would still cycle too much, and trip out the protection circuit in the freezer.  I solved this with a staggeringly simple method; put the probe in a gallon jug of regular water that also contained a rod thermometer.  The theory is that the water will hold and gain/lose temperature more slowly than the air, thus widening out the cycle and allowing the protection circuit time to cool off after shut-off.  Voila!

[TeeDubb]

It's a little hard to deduce with the information provided. Older refrigerators could have high inrush currents when they start up and that may not play well with other equipment. Extension cords and the power meter could increase voltage drops during starts and cause problems. If it were me, I would first move the fridge closer to the outlet (eliminate the extension cord). Measure the power draw using your meter with just the fridge operating normally by itself. Then I would look at are the current (amp) capacity of the Johnson Temp controller vs. the fridge. If the fridge has big current spikes, maybe the temp controller is protecting itself thermally.

[cmargeson]

Thanks for the reply!  Okay, that would make sense, I can definitely try what you recommended by eliminating the extension cord.  What other information do you need to make a more educated guess?

[KellerBrauer]

Hey Everyone,

I've gotten a big old Kenmore chest freezer from a guy in my homebrew club, that I'd like to use as a fermentation and lagering chamber.  Works fine, just old.  I also have a Johnson analog single-knob external thermostat.  The external thermostat/freezer are plugged into an extension cord, which is also plugged into a voltage/wattage meter (I'd like to know how much running this ancient leviathan will cost me).

I've tried running it at 50 degrees, but it'll get it down to temp once then, pfft, won't cycle, and gradually get warmer.  If I start the freezer off cold, then let it rise, same story.  But when I remove the external thermostat and just plug it in, runs and cycles fine.

When I twist the knob on the thermostat, the freezer will start to cycle, stop, start, then finally quit.  Again, take away the thermostat, works fine.  Any ideas what is going on here?

I’m trying to envision your setup, but can’t.  Are you saying the fridge is plugged into the Johnson Control external thermostat and the thermostat is plugged into the extension cord?  Or, is the fridge and JC thermostat plugged in separately and independently?

What needs to happen first is to jump out the chest freezers internal thermostat.  Now you know that stat is not doing any control of the compressor.  Next, you need to use your JC external thermostat to control the compressor by building a means to plug the fridge into a receptacle that is powered by the JC t-stat.  For example:

https://www.amazon.com/Inkbird-Max-1200W-Temperature-Controller-Greenhouse/dp/B01HXM5UAC/ref=sr_1_1_sspa?crid=1VRS704QYTJOQ&dchild=1&keywords=inkbird+temperature+controller&qid=1589200571&sprefix=Inkbird%2Caps%2C387&sr=

This device will take control of the compressor when the fridge is plugged into the Cooling receptacle of the controller.

If, by following these instructions, you still have problems, than I’m having a mental block on exactly how your devices are being used.  Perhaps you can then clarify?

Hope this helps!

[cmargeson]

https://imgur.com/tuPt2Yn
https://imgur.com/6KQn5a7
https://imgur.com/lANhij2
https://imgur.com/jJVx2oB
https://imgur.com/JRuCX34
https://imgur.com/4h0kXjy
https://imgur.com/nhY1ykk
https://imgur.com/v6C64MA

Sorry, guess some pictures would help, but yes.  The power chain is power meter>extension cord>external thermostat>freezer.  Hit the link for pictures of everything.

[KellerBrauer]

https://imgur.com/tuPt2Yn
https://imgur.com/6KQn5a7
https://imgur.com/lANhij2
https://imgur.com/jJVx2oB
https://imgur.com/JRuCX34
https://imgur.com/4h0kXjy
https://imgur.com/nhY1ykk
https://imgur.com/v6C64MA

Sorry, guess some pictures would help, but yes.  The power chain is power meter>extension cord>external thermostat>freezer.  Hit the link for pictures of everything.

Okay - good information so far. However, I still have questions:
1) Can you provide a complete picture of the Johnson Control?  It would also help to have the Model, range, rating, pole type (SPDT, SPST, DPDT, etc.?)
2) What is the device with the Williams Brewing sticker?  I cant find any reference to that number on the Williams Brewing website.
3) One of the pictures has a "probe".  Is that the sensing probe for the JC Controller?

My initial reaction is the JC Controller is trashed or is not being used in its intended purpose.  However, before i make that determination, i would like to get more information from the above questions.

[a10t2]

I've tried running it at 50 degrees, but it'll get it down to temp once then, pfft, won't cycle, and gradually get warmer.

How long have you waited? The analog Johnsons have a fixed short-cycle prevention; IIRC it's 10 or 15 minutes.

Other than that, there's nothing to adjust and it sounds like a broken controller. The good news is that Inkbirds sell for about $30 on Amazon; the bad news is that like TeeDubb said, the compressor startup spike on that beast will probably fry any 10 A relay eventually. You can also pick up a 25 A SSR and heat sink on Amazon for around $20.

[TeeDubb]

What needs to happen first is to jump out the chest freezers internal thermostat. 

To simplify this step, you can also turn down the freezer's internal thermostat as low (as cold) as it will go.  That should prevent the two from conflicting with each other. If you still have issues, I would upgrade the external Johnson controller with the brand noted by others. Most are in the 10A current rating range, but there might be a version with up to 15A.

[cmargeson]

@KellerBrauer - !. Okay, found the device spec sheet, here: https://cgproducts.johnsoncontrols.com/MET_PDF/2476642578.pdf
2. I think it was sold through Williams Brewing.  The "A19AAT-1" model number is correct though.
3. The probe in the picture goes to the JC unit.

@a10t2 - I've waited a couple of days, it don't do what it's supposed to do.  The good news is that this JC controller is rated to 15A, so no frying here.  And (theoretically) there is a way to adjust the short-cycle.  But the InkBird does look like a nice solution.

@TeeDubb - I'll crank the internal thermo way down, but to be honest, I think the voltage drop from the extension cord is what the problem might be.  Next step: move the freezer over to the outlet.  Which I don't want to do.  Because it's huge.

[KellerBrauer]

What needs to happen first is to jump out the chest freezers internal thermostat. 

To simplify this step, you can also turn down the freezer's internal thermostat as low (as cold) as it will go.  That should prevent the two from conflicting with each other.

Not necessarily.  You’re making the assumption that the internal thermostat works.  In this case, the thermostat may not work and simply turning it down may prove moot and conceal the actual problem.

[KellerBrauer]

@KellerBrauer - !. Okay, found the device spec sheet, here: https://cgproducts.johnsoncontrols.com/MET_PDF/2476642578.pdf
2. I think it was sold through Williams Brewing.  The "A19AAT-1" model number is correct though.
3. The probe in the picture goes to the JC unit.

@a10t2 - I've waited a couple of days, it don't do what it's supposed to do.  The good news is that this JC controller is rated to 15A, so no frying here.  And (theoretically) there is a way to adjust the short-cycle.  But the InkBird does look like a nice solution.

@TeeDubb - I'll crank the internal thermo way down, but to be honest, I think the voltage drop from the extension cord is what the problem might be.  Next step: move the freezer over to the outlet.  Which I don't want to do.  Because it's huge.

I have reviewed the documentation and don’t see any issues with the JC Controllers intended purpose as it applies to your needs.  However, you still need to take the existing thermostat out of the circuit.  The existing thermostat uses a gas filled sensing element attached to the evaporator coil.  The gas in the element is typically the same gas the machine uses to generate cooling.  For example:  if the refrigeration system runs off of R-12, the sensing element gas is also R-12.  In some cases, the sensing element is actually connected (piped) to the refrigeration system in such a fashion that would be detrimental to the refrigeration system if the sensing element is damaged, cut or kinked. So DO NOT remove the internal temperature control.  For now, just jumper it out as I indicated previously.  Then run the machine again — assuming you eliminated the extension cord issue — and let’s see what happens.

A note regarding the extension cord, if the cord you’re using is a 12 gauge, with ground, cord, 25’ or a little longer should not cause any issues for you.  If you had a receptacle next to the machine, it would most likely be wired with 12 gauge wire also.  So it’s a non issue.  So, check the cord.  If it’s a 14 gauge cord - no good.  Replace it or move the machine.  12 gauge copper wire is good for 20 amps at 120vac.

If the machine still fails to operate, the problem may be in the JC controller.  Or the problem may be with the compressor overheating and tripping out on “overload”.  Now, overload may have two causes.  First, the condenser fan motor is bad and the compressor is overheating.  Or, the compressor itself is simply bad.

I’m getting windy here.  Sorry.  So let’s follow the steps I’ve outlined and take it from there.  Good luck and be careful!

[cmargeson]

Problem solved!  It took a week of careful watching, but the ancient freezer now holds temp steady at 50 degrees.  As it turned out, it was a three-part problem:

1. @KellerBrauer was right (so were others), the standard 14 gauge extension cord I was using had too much amperage drop-off; by moving the entire freezer over to the outlet, the freezer would cycle normally.  That thermostat though. . . .

2. @a10t2 - The thermostat WAS working, but it was way off calibration.  I spent a few days playing around with temp settings, and found that if I set it for 46 degrees, it would cycle the freezer and hold the temp at 50 degrees.

3. @TeeDubb - It would still cycle too much, and trip out the protection circuit in the freezer.  I solved this with a staggeringly simple method; put the probe in a gallon jug of regular water that also contained a rod thermometer.  The theory is that the water will hold and gain/lose temperature more slowly than the air, thus widening out the cycle and allowing the protection circuit time to cool off after shut-off.  Voila!