Failed Fermentation Chamber?

Alright so I was proud of myself for finally building my fermentation chamber. Much needed after freezing the entire apt with a/c for nearly a year. I've attached a few pics for reference.







Its a 33"x28"x24" block. Simply made with 3/4" insulation, toothpicks, weatherstripping, and duct tape. Nothing too fancy since I didn't intend to make anything permanent. I was hoping to cool it with the 2.7cuft mini fridge, plugged into a programmable thermostat, with a small fan to circulate. Initially it looked promising as the temp dropped a few degrees within 20-30 minutes or so. Ambient temp in the room was 73-75. Well after about 2 hours the fridge was still on constantly, a quick check showed it was still only around 67. I opened it up, and moved the thermostat to the floor in hopes that it was the rising hot air causing the issue.

Let it go overnight, wake up and its still at 67 (10 degrees from the ambient now). Fridge on, ice building in the freezer. I'm calling it a fail right there. After work today still the same temps. The fridge is pretty silent in comparison to what it normally sounds (I could be making this up). When I unplug it there is a trickling sound that doesn't go away.

I figure I blew the compressor or something either by having it insulated poorly and the fridge running constantly. Or from tipping it a little while moving it (not completely just on an angle). The inside walls of the fridge are warm. But the freezer portion is frozen and no water has dripped down so I'm not sure. I guess I'm confused because i've seen a few work bench chambers using the small cube mini fridges.

I checked all the edges of the insulation is. There is duct tape over every seam, and weatherstripping along where the top meets the sides. With everything closed I can't feel any hint of cold air from any of the seams. The only real issue I can think of is the bottom is carpet. But can that really suck out that much cold?

So point out all my issues. Not enough insulation? Is it okay and a 7-8 degree drop is all I can expect? Did I kill my fridge? Kind of disappointed. Not only do I still not have a ferm chamber, I lost my beer fridge, and my A in heat transfer now looks pathetic.

The carpet is not going to be much of an insulator. Put a piece of foam down for the bottom.

Point your fan at the freezer portion.

That is definitely not insulated enough. Put at least one more layer, preferably 2, of that pink board on all 6 sides and seal up the cube good and airtight.

Should work fine once you do that and completely defrost that fridge. By work fine I mean you should be able to maintain a 15-18 degree differential from ambient.

Sounds good, I guess I didn't do enough research andwas too optimistic. I'll pick up some more tomorrow, add another layer or two along with a solid surface bottom. Just hope I didn't kill my fridge in the meantime. Thanks for the support.

The key to making this work is air tightness. You may not see or feel a small air leak and it only takes a tiny leak to cause major problems particularly with the evaporator icing up. I would tape all of the seams inside and out. Might not be a bad idea to caulk the seams before you tape them up. I also agree that you could use a lot more insulation and the floor is a major source of heat infiltration. Don't give up just yet.

Sounds like all you did was build up excessive ice on the freezer. This will happen if there is too much moisture in the air relative to the heat load.