My Ranco controller will only go to 43F! Help please.

I have a couple Bohemian Pilsners in my fermentation fridge right now, and I'm having a tough time bringing them down to lager temps (35-40F). I set my dual stage Ranco down to 35 with a one degree differential between the heating and cooling (34 and 35), but the fridge seems to click off as soon as it gets down to 43.

I'm using one of those old Hotpoint refrigerators. Anyone else have this problem? It has been very warm in my garage the past few days, but I would think it would just keep running until it gets down to where I set it. Why is it turning off? Any ideas would be appreciated. Thanks!

Remove the Ranco and use the refrigerator's control. 35-40F is nominal for any fridge. This will also let you know if the problem is the fridge itself.

Yeah does the fridge have its own thermostat control? Maybe that is kind of overriding things.

Hmmm... these seems like good possibilities. I have the internal control of the fridge dialed up to the coldest setting. I guess I thought the Ranco would override that and keep it running until the temperature probe read 35 F or so. Am I wrong to assume this? I just unplugged the fridge from the Ranco and plugged it back into the regular outlet, and left the probe taped up to the side of the carboy. I'll post back later and see if it changes things.

Joeneugs said:

Hmmm... these seems like good possibilities. I have the internal control of the fridge dialed up to the coldest setting. I guess I thought the Ranco would override that and keep it running until the temperature probe read 35 F or so. Am I wrong to assume this? I just unplugged the fridge from the Ranco and plugged it back into the regular outlet, and left the probe taped up to the side of the carboy. I'll post back later and see if it changes things.

Click to expand...

All the ranco does is turn the fridge on and off. It does not directly control the refrigerator.

So what you mean is that even though the fridge is on (I can tell because the light inside turns on when I open the door) the compressor that runs the cooling is turning off because of some internal control? Is there any way I can over ride this so that the compressor will run until I get down to the proper temp?

Joeneugs said:

So what you mean is that even though the fridge is on (I can tell because the light inside turns on when I open the door) the compressor that runs the cooling is turning off because of some internal control? Is there any way I can over ride this so that the compressor will run until I get down to the proper temp?

Click to expand...

Unless you actually bypass the internal thermostat on any chilling unit (fridge, freezer, doesn't matter) an external controller will never get that unit any colder than the internal thermostat allows. In your case it sounds like the internal thermostat is limited to 43°F.

A couple of options: you could find the wires to the internal thermostat, disconnect them from the thermostat and wire them together, at which point the unit will entirely depend on the external controller. Or, you may be able to adjust the internal thermostat to extend the range downward. Check this thread out for the latter...

Cheers!

+1 what day_trippr said. My kitchen fridge's temp setting ranges 33F-46F. My kegerator in the garage is an old fridge someone gave me and it's set around 38F. So if you can't get it below 43F with it set on its coldest setting, it makes me think you have a bad thermostat (in the fridge, not on the Ranco). There might be a coarse adjustment screw on the fridge thermostat that you could try adjusting to get the temp lower, otherwise I'd do as day_trippr said and bypass it altogether.

Wow. Thanks for that link! I already read through the first 13 pages, and it seems to be exactly what I need. I guess since I already have the controller, the best thing to do would be to disconnect the internal thermostat altogether. Would the compressor automatically turn on as soon as the fridge turns on? (if being controlled externally?)

Well I got to the thermostat, but I'm unsure how to properly disconnect it. It's not connected by wires, but these single prong plug type things (sorry... I'm a really lousy electrician). Can I just yank them from the thermostat and let them dangle? Day trippr said something about wiring them together in his post above, but how would I do this?

Honestly bro I would use that fridge to server your beer and get yourself a chest freezer for lagering/fermentation. It would save you a lot of headache. Other than that sorry I don't know how you would wire it.

Ok, I'm in need of serious help now. I really screwed up my fridge. I messed around with the thermostat too much and now the compressor won't come on at all. I tried backing out the coarse adjustment screw (to make it colder) and nothing is working now. When the fridge is plugged in I can hear clicking noises coming from the thermostat.... I know that can't be good. Does anyone know of anything I can do at this point? Is there a way to disconnect the thermostat and still have the compressor come on when the fridge is plugged in? Help please!!!

I would start by tracking down a wiring diagram for the fridge- look up the model on line or look on the back- usually there is an envelope or something like that taped to the back. Not all stats are just a simple switch that can be jumped out, but some are. If you have two lines going to the stat, then that's likely the case, in which case, just cut, strip and wire nut the wires together and you will be bypassing the switch and the compressor should run because it thinks that the switch is always closed. do this with the fridge unplugged, of course.

Find that envelope that spearko520 mentioned, take a pic, and post it here. Someone will help you. Here's a tip for the future. Don't mess with electronics if you don't know what you're doing. Not only can you get hurt, but you can ruin things People here are always glad to help. Just need to post wiring diagrams or at least model numbers of what you have.

In most cases, the thermostat is just a fancy on/off switch with a circuit that is either open or closed. If you're using the Ranco you can bypass it. In mine there's a black, white and green wire. I connected the black and white together. Left the green (ground) alone.

But, seriously, like IrregularPulse said, if you're not sure of what you're doing, leave it to someone who is. I used a volt meter to be sure of what each wire did before messing with anything. It's not worth the damage, fire, death . . .

Thanks for the replies. I talked to an appliance repair guy and he said the same thing you all are saying. I'll try wiring the leads together and see if that works. I've been doing all this with the power supply disconnected of course...

So it looks like that finally worked. I cut the leads going to the thermostat and just wired them together. The compressor now runs a lot longer and the fridge is down to 37 F and should fall a bit more in the coming days (100 degree heatwave is over). Oddly, the compressor still shuts off from time to time, but not for very long. Maybe it automatically shuts down if it gets too hot??? Anyway, I'm happy with the way it is now. I think I'll post my experience in that other thread referenced earlier, since nobody mentioned that you can't adjust the thermostat on these kind of refrigerators.

Cheers, and thanks again for all the help. This site rocks!!!

there are thermal switches in compressors that reset automatically when they get to hot (like the ones in canister lights). Sometimes there are manual thermals with reset buttons or switches. Glad you are cold!