Well its been in the 100 Deg. range here in Southeastern VA. I ferment in my detached garage which stays fairly cool normally and it has A/C which I only run when I'm at home. Temps are climbing and keeping my fermenting brews cool is getting to be a problem. I built a ferm chamber underneath my work bench with pink foam and put the carboys in a container of water and changed out the ice about 3 times a day but I still have trouble keeping them below 70 deg.
What I would like to do is I have a very old Hotpot upright freezer in my attached garage. It' the kind with an external condenser coil and the shelves are the cooling coils so there is no moving them. What I was thinking is building a ferm chamber next to the freezer and cutting one hole through the bottom side of the freezer and another higher up. Them use some ducting to the ferm chamber.
Anybody ever try this? I pretty sure there is nothing in the sidewalls of the freezer except insulation.
Would convection be enough to circulate the cold air? If not how could I temperature control a computer fan or something similar? SWMBO wants to keep using the freezer for our food. So no tearing it apart. And since my recent keezer build I need something inexpensive.
I also built a ferm chamber of pink insulation and plywood under my workbench in the garage. I picked up a used window AC unit off CL for $40, cut a hole in my ferm chamber wall, and mounted the AC unit.
The AC unit is connected to a Johnson digital controller, with the probe taped to the side of my carboy. I had to reroute the AC's internal temperature sensor from the front grill out the back of the unit so the compressor wouldnt kick off when it sensed that the ambient temp of the chamber was getting cool, but that was super easy. Just popped the grill off, unclipped the probe, and fed it back through the control panel and out the back of the unit.
It keeps perfect ferm temps even in my garage in oklahoma summer weather! Much cheaper/easier than chopping up your freezer I'd think...
Heres some photos. Note: I do not claim to be an expert wood-worker by any means. The water stains on the floor are from a previous incarnation of this unit. Always make sure your AC unit is angled so it drains out the BACK
If you cool your wort to ferm temp BEFORE it goes into the chamber, then the AC unit only cycles on for about 3 minutes every hour or so when its hot outside. During the spring time it cycled on for about 3 minutes every two or three hours. As long as you insulated your box well then the AC unit is only there to drop the temp 1 degree about once an hour or so, depending on outside temp. The heat it outputs doesn't affect the temp of my garage at all...but my garage is pretty much above 90 at all times during this part of the year.
You could duct it outside since you have AC in your garage, that seems like a simple solution.