Help! Cryo freezer not dropping in temp... troubleshooting

So first off I’d like to say that i essentially have little understanding of refrigeration.

I didn’t go into the lab for a few days and I returned to the machine shut off the night prior, so I turned it back on and came back to it about an hour or so later to see it still sitting at 14c. Before leaving i had the freezer down to -55 and the volt meter on the unit was reading 242v. Initially i was able to get the freezer down to -76 (its low on refrigerant as it should get to -80) and the volt meter on the unit was registering 232v. i have been told that even though the plaque on the side of the unit reads 208/230v the number on the unit was ok - if this isn’t true please set me straight.

the model of the unit is ufrc1386-7-d12

i can find all of zero info on it for troubleshooting; the closest i was able to find was this:

the temperature failure light has been on - this was due to the temp not being @ the set point (-76) or below the alarm set point (-67) as it went off when it hit the target

the alarm battery light is on but its because the little 12v battery is sulfated and needs to be replaced (or so i believe)

I checked the fuse in the bottom and the “check fuse” light went on when i removed it.

I’m not sure if there are 2 compressors in the unit - a high and a low? - but perhaps a/the compressor has a problem?

maybe there is a refrigerant leak?

what else could it be?

All help is MEGA appreciated, so thank you in advanced :slight_smile:

I wouldn’t go running around hooking gauges up to it just yet! Our cryo freezer takes forever to get down to about -20F before it really starts to get going quick. I’d leave her plugged in overnight first and see if it gets down to temp. I don’t think the control systems let them run very effectively at higher temps

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yeah im gunna check it tomorrow afternoon. however my worry comes from when i initially started it up and such it took maybe 30 mins to drop from 18c - 11c then less than 24 hours to hit -76 and after an hour today it just sat at 14c which is where it was at when i turned the power back on. For sure am hoping its just nothing and a weird little blip… fingers crossed

Can you feel either of the compressors running at all when you plug it in?

I can hear at least one - if there is in fact two - kick on after a few seconds when the power is turned on

I’d let it run and we’ll get into it tomorrow if it doesn’t get cold. It will definitely have two refrigerant circuits, it’s pretty much the only design for those fridges. You’ll have a hard time telling if the second one is running though once the first one has kicked on

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Hmm yeah it’s kicks on louder and then goes quieter and I’m pretty sure I remember it being louder the whole time, but again I could be remembering wrong… we shall see tomorrow :grimacing:

For what it’s worth, the volume combination you should be most afraid of is very loud followed by complete silence lol

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:joy: haha ill post up a video tomorrow of it turning on, to boot

What is the ambient temp in your workspace these days? My -86 freezer fell on it’s face when my workspace went above 28C (84F) in the summer.

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Between 12-18c

Your first stage compressor may not be chilling. And if that one can’t get cold enough, the second stage compressor can’t begin to chill. I’ve had a very similar experience with a julabo fw95

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Yuck… hope that’s not the case. Is one compressor larger than the other? I’ll get right down and get some good video/shots tomorrow

Added a shot of the stickers on the side of the machine showing any relevant info to the original post

Take everything in the freezer, out of the freezer

They’re not designed to remove all that heat energy while also dropping down to temp

Once it’s down to an acceptable level, begin loading the freezer, don’t stress it too hard

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Just a couple of SS pots, but I’ll be sure to remove em in the morning :call_me_hand:t3:

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How much stuff is in the freezer just sitting there, being warm ?

Edit: answered

Hmm okay that is odd

They DO take a long time to get to temp//

Try filling those SS pots with dry ice to give it a boost, they do like to just maintain their temps and aren’t into all the work of pumping heat out from high temps

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Ya I’ll have to see how it is tomorrow and go from there. The dry ice method may be a help in the meantime, should a compressor be an issue

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Feed the boy some ice, good boys love ice

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One compressor is probably r404 and that will get you down to -40. The next compressor can’t kick in until it gets close to that temperature.

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