Don't know what's wrong with my STC-1000

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SMOKEU

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I have a an STC-1000 (Mangrove Jack's one) connected to my brew fridge and heat pad. I've done many brews with this setup without any issues. Today I was cold crashing my IPA and the temperature was stuck on around 10.5-11.5C according to the STC, but the top of the beer had ice on it and my IR temperature gun was reading temperatures below freezing. I unplugged the STC-1000 and reconnected it (at one stage I had it fully unplugged for hours) and it's still doing the same thing.

I then replaced it with another STC-1000 and that controller is reading the correct temperature as expected.

I took the "faulty" STC-1000 into my bedroom and it's reading accurately according to 2 other thermometers I have. I put the temp probe outside the window even and it's reading around 8C, just what it should be reading. No idea what went on here. I always tape the temperature probe about 2/3 of the way to the top of the fermenter, and then put some foam over the top to insulate the probe. I didn't do anything different to all the other batches I've done.

Luckily I caught it in time as there's only a very small amount of ice covering less than 20% of the surface.
 

day_trippr

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Cool side relay points might be welded. Was the unit displaying it was in Cool mode when things were frozen?

Cheers!
 
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SMOKEU

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Cool side relay points might be welded. Was the unit displaying it was in Cool mode when things were frozen?

Cheers!
Yes, the unit was still in cooling mode when it was frozen (according to the LED on the STC), and it was reading at least 10C higher than the actual temp. I've had that STC in my bedroom for a few days with nothing connected to it and it seems to show accurate temperatures...
 

day_trippr

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Might just be a wonky probe. I think you can still get oem replacements for them, but if not you need a 10K NTC B3435, which is a common type...

Cheers!
 

Nagorg

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FWIW... Break/Short in thermistor wire >= "Wonky Probe". :p Get another thermistor!
 
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