tl;dr: Frost-free fridge turned off one night for an extended period. Tried several times throughout the week to plug it back in with no luck. One time I left it plugged in for several minutes and then it suddenly kicked on. Any idea what's wrong with it? Long version: Got a fridge off craigslist and hooked it up to a Ranco controller with a 200W space heater inside. It's out in an insulated but detached shed. While fermenting at 66F, I gave the fridge a 1F differential. When I dropped to 45, I didn't want to work it too hard, so I set it at 44 with a 2F differential. It worked for almost a month, then I went out one morning and discovered it had stopped overnight and gotten up to ~57. It wasn't that it was running but not cool, it just sat there doing nothing, making no sound. I went out tonight (~one week later) to try to fix it. I plugged it in and tried to put in a new lightbulb to see if I could get that to come on (the light had never come on before anyway). About two minutes after plugging it in, the fridge suddenly kicked on again. I'm relieved that it still (sort of) works, but I don't want it to get temperamental again and spoil a beer. Any idea why it would throw this kind of tantrum or any way to prevent it? Is that the frost-free cycle? Need more coolant? Too humid outside? Just a lousy fridge?
I think you lost me.... It sounds like you're trying to protect against high ambient temps as well as low ambient temps in your shed, so you are using a heater inside a fridge in combo so that you can heat and cool the inside of the fridge? When you dropped the control setting to 44 did you turn off the space heater? (Is your space heater a big light bulb? I'm unclear why you mention a light bulb.)
My first guess was that the differential was set too low, if a compressor ties to start too soon after shutting off , it will pull too many amps and go off on an external or internal overload. It's strange that after a week it still took 2 min to start after plugging it in. Maybe it still had a few minutes left on a defrost cycle. I'm wondering if the addition of the space heater to the circuit is causing an overload? The compressor may be weak/tired . If it was my call, I would get rid of it.
I see lots of troubles with fridges and controllers, but can't recall any threads about how their freezer went haywire with the controller. I have freezers and haven't had any issues. Well I did have a little bit of an issue when the thermostat in my bro's house went haywire and quit working during an ice storm, and I had no way of heating set up. So my beer got a bit cold-crashed, but it made little difference as it didn't freeze and primary had already been done for at least a week on both batches. Having things get too COLD is a very rare thing down here. If you're trying to heat and cool from within the fridge all one one sensor, one circuit, that could be the trouble. By 2F do you mean setting the heating and cooling circuits 2 degrees F apart? And are you certain the different circuits are calibrated similarly? If they are fighting each other that might be why the asplosions. But then I am not an electrician so don't take my word for it.
It's a two-stage controller. If the temp hits 46, the fridge drops it to 44; if the temp hits 43, the space heater warms it to 44. I'm not sure that's important to the fridge breaking, but thought I'd explain in case it was. The light bulb I'm referring to is just the one that comes on when you open the fridge door; I was trying to see if power was still going to the fridge. What differential do you use? I think I've seen people use 1F, but maybe that's only inside. How exactly does the defrost cycle work? I would hope it wouldn't be off so long for that as to go up 10F, that doesn't sound safe for food.
Power from the wall goes to controller, which directs it to either fridge, heater, or neither. Both set at 44 F, but the fridge is allowed to get up to 46 before it kicks on while the heater will only let it down to 43.
thats a pretty tight temperature range for the fridge to operate within, not to mention that the way most are gonna work is to get below their set point to turn off. Which in your case is 43F, at which point your heater immediately turns on. The heater is gonna be on for a while before it warms the air in the fridge up to 44F (unless you have a fan) and you likely overshoot your upper temp quickly. Basically your creating an endless heating/cooling cycle, and IMO keeping that tight of a temp tolerance for the ambient air in the fridge is not necessary Id say get rid of the heater and bump up your temp range to at least 3F. If your worried about swings in the fermentor put it in a big bucket of water within the fridge
I needed the heater at first because we were getting nights colder than I wanted the beer to go. I guess it's not really necessary any more, but as a result it never really kicked on in the last couple weeks. The fridge does turn off without turning on the heater. The heater does have a fan in it, that's why I picked it instead of the light-bulb-in-a-paint-can heater. I'd like to have heat as an option though in the fall. My understanding was lots of people have this sort of setup but maybe with a different differential? I didn't really measure, but I'd estimate the fridge would run for ~15 minutes to get from 46 to 44, then stay at 44/45 for half an hour before needing to kick on again.
I see. Does seem like a tight range. But then I have never found anything electronic to be all that reliable, and the more complex, the less reliable is the general rule. You could try giving it flying lessons, that's what I usually do when something electronic pisses me off.
I might have it. The fridge was on the warmest thermostat setting, which cuts off right about where I had the controller set, so the thermostat inside the fridge might have been cycling the compressor more often than the controller. I'll see how it goes with the fridge thermostat all the way to cold.
Good call. You want to give the plug-in controller complete control. Ideally, you want to bypass the built-in thermostat completely. Turning the fridge down to max cold effectively does that.
whenever you are having temp control problems and you are using an outboard thermostat, you want to reduce all the variables and work up to the point where the problem occurs. so remove the Ranco. turn on the freezer and operate like a regular chest freezer (without beer). set it to its warmest temp setting and leave a thermometer inside. should get to below 32, even set to "1" or whatever is the lowest. if everything is ok, then re-install the Ranco and diagnose the problem. my first thought is that the Ranco was not over-riding the internal t-stat or is just at the same cut in/out temp. it should be set to a little above the warmest setting. this way if the if the Ranco craps out you don't have -10 beer. Cheers.
I like to set differentials at about 4 deg. From reading your first post it sounded like the defrost cycle had already started before you unplugged the frig. then when you plugged it back in, it had 2 minutes left then started. The cycle shouldn't last long enough for the temp to go up 10 deg.
