BM23 overheating or faulty thermostat?

[jackstraw]

I have a new BM23-S-31 that is installed outside. I never noticed overheating with the old BM23 I had installed in the same place. But I'm suspicious because I know the airflow isn't great behind the unit. It is under a counter, but the space is not that tight. I know this unit vents in the back and not the front. But again, I never noticed an overheating issue with the old unit that used to be there. To be safe (or so I thought), I got two 80mm PC fans and attached some 3" ducting and put them under the unit to suck warm air from the back and blow it out the front. That seemed to be pretty successful. I put an air thermometer probe at the back of the cavity, and my PC fans seemed to drop the temperature in there by almost 10 degrees. It's about 70F air temp.

So let me get to the problem... It's been running for a week with this setup. I have a 5 gallon bucket of water inside. I adjusted the thermostat to about 3.75, which put me around 37 to 38 degrees liquid temp. All is good and I'm excited to tap a keg. I walked by the unit about 10 times over the weekend and 8 of those times, the compressor was cycled off. So that's a good sign that it can maintain temperature without working too hard. Then last night I went to check on it and the compressor was running, I opened the door to find that the entire bucket of water was frozen solid!

So here's my question. If the compressor just keeps running to the point of freezing everything inside, does that mean it's overheating? Why wouldn't the thermostat do it's job and shut the compressor off? Or do I have a faulty thermostat?

Thanks for the help.

[psychodad]

From what you described, I'd say you had a thermostat malfunction.

[PointPleasantNJBeerguy]

see if compressor turns off when dial turns to OFF. These units should be operating @38F with dial set at approx 5.

[jackstraw]

Yes, the compressor turns off, when I turn the dial to 'off.' I left it in the off state (with only the evaporator fan running) for 12 hours yesterday. For this unit, setting the dial to just under 4 (maybe 3.9) gets me to 38F. If I go too much over 4, I get a thin layer of ice on my bucket of water. Last night I turned it back on, checked it this morning and I was at 38F and I also noticed the compressor was cycled off.

So if it was a thermostat malfunction, is that typical of the BM23? Seriously, it froze the ENTIRE 5 gallon bucket of water. I would not be happy if that were a new, full keg.

As I mentioned, I'm a little paranoid about keeping ventilation moving behind the unit, since it's in a semi-enclosed space. But how do I know if I have a problem? From my understanding of refrigeration, if the unit is not properly ventilated, the compressor runs long enough to generate enough heat to prevent the internal temp from getting down to my target 38F. So I would know if I'm overheating if the fridge isn't getting cold enough and the compressor does not cycle off. Is that correct? My question for the pros, is there a potential overheat problem, where I would see the internal temp just keep getting colder? I'm not an expert, but I would think if the internal temp keeps dropping, the thermostat would tell the compressor to shut off.

One other thing I'll mention, which may not be an issue. When I got the unit, I uninstalled the railings on the top. To do so, I removed the top of the unit to access the screws. While doing so I was surprised to notice the evaporator coil was a bit smushed/dented on the top for a few inches. I'm guessing this happened at BevAir when they assembled the unit. That metal is super thin, I didn't mess with it, because I didn't want to do more harm than good. I figured if it really were damaged, the unit wouldn't cool properly. But that doesn't seem to be the case.

I picked up this unit at a discount from the retailer because it had some superficial scratches on the top and back. Hoping I didn't buy a lemon. :/

[PointPleasantNJBeerguy]

Is it easy to pull unit out and try running out of the cabinet enclosure?

[jackstraw]

Yeah. That's a good idea. I can do that this weekend.

[jackstraw]

Same behavior out of the enclosure. The compressor just runs continuously now and will not shut off. The thermostat will shut off the compressor in the "off" position, but not in any other position... Even at 3, it gets so cold, the 5 gal bucket of water freezes solid.

Sounds like a faulty thermostat?
Could it be anything else?

I guess I'll be making some warranty calls this week.

[PointPleasantNJBeerguy]

At this point I would say Thermostat..

[jackstraw]

Yes. I think you're right. I spoke with Bev Air this morning and sounds like they're going to arrange for a tech to come out and replace the thermostat. Have to say, I'm a little surprised that the thermostat would work just fine for the first week and then fail.

[jackstraw]

Problem seems to be fixed. Bev Air had a local service company come out and replace the thermostat. That seems to have done the trick. Just posting in case anyone else runs into the same problem.

[PointPleasantNJBeerguy]

Cool...Good thing only a small fix..