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wlw33
02-04-2015, 08:20 PM
Hi all,
Ran into a new problem today. Our walk in cooler was down to 15 degrees F today! We have an 8000 btu AC that we have been running since July with no issues. All of a sudden the room was down to 15 and we had frozen beer in our kegs. We have it turned off for the night (temperature of the rest of the floor is around 50 right now. Has this ever happened to anyone before? The coolbot was set to 37 and there was no ice on the fins. Definitely at a loss and I can't find anything online.

TGTimm
02-05-2015, 10:22 AM
Other than your thermostat going gunny-bag, I have no idea.

But--check your kegs for freeze damage! We've rarely seen damage unless the kegs got to below 10F, but the consequences of a damaged keg are severe. Look for swelling on the tops and bottoms of the kegs. Kegs are certified pressure vessels, and potential bombs if damaged.

Rick500
02-05-2015, 11:33 AM
Wow, that's pretty impressive actually. Sorry to hear you had trouble though.

We're getting ready to fire up our CoolBot-operated walk-in pretty soon, with 36,000 BTUs between 2 AC units. Hopefully everything goes well.

wlw33
02-05-2015, 04:06 PM
Other than your thermostat going gunny-bag, I have no idea.

But--check your kegs for freeze damage! We've rarely seen damage unless the kegs got to below 10F, but the consequences of a damaged keg are severe. Look for swelling on the tops and bottoms of the kegs. Kegs are certified pressure vessels, and potential bombs if damaged.

Thanks for the tip. All looks well.
I think I may have found the issue. Coolbot not a problem. Like I mentioned I turned everything off overnight and just got back to it. I plugged the ac unit and the compressor started running (huuummm) even without being turned on. No air coming out just running. My guess is that the computer somehow is telling it to always be on. I'm testing it now to see how cold it gets while I'm here.
Does this sound familiar to anyone? Confused as to why an ac unit would do this. Maybe it's just tired from being run almost constantly since July.

panadero
02-06-2015, 07:05 AM
Coolbot people are pretty responsive, they may have an answer for you.

Rick500
02-06-2015, 10:08 AM
What AC unit do you have?

wlw33
02-06-2015, 02:48 PM
What AC unit do you have?

It's a Sharp Comfort Touch, 8000 BTU. I can't find anything online related to this problem.

wlw33
02-06-2015, 03:59 PM
egI eventually got it running normal (I didn't do anything to it, it just worked itself out) but I'm really worried about letting it run. Luckily our basement is cool and our walk-in is crazy insulated so when we don't run it, it still sits around 41-42 degrees. I'm just worried if I leave it'll funk up again and freeze our kegs while no one is here. So weird. This is really not a coolbot related issue, as all the coolbot really does is make the AC control unit think it's warm-the lowest you can set the coolbot is 32*.

panadero
02-06-2015, 04:11 PM
We had an issue where our coolbot temp probe was reading incorrectly. They replaced it overnight, (talked us thru troubleshooting) I believe, and our problem was solved. We have an extra coolcot unit sitting around for those times when everything else doesn't work that should. It has helped a few times. Three years in running a 12000btu ac.

wlw33
02-06-2015, 04:44 PM
We had an issue where our coolbot temp probe was reading incorrectly. They replaced it overnight, (talked us thru troubleshooting) I believe, and our problem was solved. We have an extra coolcot unit sitting around for those times when everything else doesn't work that should. It has helped a few times. Three years in running a 12000btu ac.

I get that totally. Our issue does not seem to be coolbot related. As i mentioned, when I first plugged the AC unit back in the compressor was running even though I had not turned the unit on. Also, I had put the unit on "FAN ONLY" which would make the coolbot effectively useless, and it was blowing cooled air. Suddenly the problem went away and it is strange to me. What would cause a compressor to just keep running and running, and then just decide it's fine and work as it's supposed to?

TGTimm
02-07-2015, 10:14 AM
Generally, the fan on a chiller unit does not run the entire time the compressor is running. I realize that the AC coolbot is a bit different critter, but the fan is usually triggered by a high-pressure switch in the refrigerant line. Most compressors also run a "pump down" cycle for a while when first starting up. This will not usually trigger the fan, but the compressor will be running.

Again, my experience is with commercial chillers--your AC unit my be a completely different proposition.

As for the problem of over-cooling, it might make sense to buy or make a Jonson A419- (or 319-) based thermostat like those sold for home-brewers. Put the sensor in a sealed jar of water, about 1 pint should be fine (this adds thermal mass to slow reaction time; the A419 also has an anti-short-cycle setting). Plug the entire AC unit into this, and you'll be able to set a minimum temperature to guard against problems in the future. If your compressor is more than, I think, 1 hp, you'll need to add a contactor/relay to the system to handle the amperage.

wlw33
02-07-2015, 02:01 PM
Generally, the fan on a chiller unit does not run the entire time the compressor is running. I realize that the AC coolbot is a bit different critter, but the fan is usually triggered by a high-pressure switch in the refrigerant line. Most compressors also run a "pump down" cycle for a while when first starting up. This will not usually trigger the fan, but the compressor will be running.

Again, my experience is with commercial chillers--your AC unit my be a completely different proposition.

As for the problem of over-cooling, it might make sense to buy or make a Jonson A419- (or 319-) based thermostat like those sold for home-brewers. Put the sensor in a sealed jar of water, about 1 pint should be fine (this adds thermal mass to slow reaction time; the A419 also has an anti-short-cycle setting). Plug the entire AC unit into this, and you'll be able to set a minimum temperature to guard against problems in the future. If your compressor is more than, I think, 1 hp, you'll need to add a contactor/relay to the system to handle the amperage.

I liked your idea about the Johnson controller so I tried it out. Unfortunately, our AC unit needs to have the power button pressed when power returns. I set the johnson controller a little higher than normal to test, and it turned the unit off as should, but when the room warmed up to the point where the controller should've turned back on, nothing happened. I pressed the power button and voila. So unfortunately this isn't an option.
It has been working fine since that one day, but again I'm afraid to chance it.

TGTimm
02-08-2015, 10:13 AM
Well, that sucks. I guess everything has to have a computer built into it nowdays, even if a simple mechanical thermostat would do just fine. Unfortunately, this also means that your coolbot will have to be manually restarted after a power outage or flicker. I'd be damned tempted to replace the controls on the AC unit with standard chiller controls--thermostat, high-pressure and low pressure switches. Your local appliance repair person should be able to do this if you don't feel comfortable with it. I've done this exact thing with one of our newer kitchen prep tables/refrigerator. The computerized controls went belly-up after a year or so, and it now wears a Johnson thermostat, which works just fine, thank you.