Just finished my first custom spot cooler — a few observations

I tried a similar setup last summer using a defunct Igloo countertop unit. Those small compressors are surprisingly resilient, but the thermal output on the back side was my biggest hurdle. Even with a small delta, the heat coming off the condenser coils usually cancelled out the cool breeze unless I had a very specific airflow path.

I ended up using a Noctua high-static pressure fan to force air through the evaporator fins. It helped drop my output temperature to about 10 degrees below ambient, which felt amazing during the July heatwave. I also found that adding a bit of thermal paste between the coil mounts and the custom bracket improved the heat transfer just enough to be noticeable. Keep an eye on that condensation tray. In my experience, if the humidity spikes over 60%, those small reservoirs overflow in no time. I ended up routing a 1/4-inch vinyl tube from the drain port directly into a five-gallon bucket under my desk. It isn't pretty, but it saved my floor from getting soaked during a long gaming session.

I ran into a massive icing issue when I attempted this with a NewAir donor unit. Since those evaporators are designed to reach sub-freezing temperatures to drop ice cubes, the moisture in my 60% humidity basement woud flash-freeze onto the fins within twenty minutes. I had to wire in a basic STC-1000 temperature controller to cycle the compressor off whenever the coil temp hit 33 degrees, otherwise, the airflow would just drop to zero.

Instead of the plastic ducting, I actually swapped the evaporator into a small reservoir of distilled water and used a tiny 12V submersible pump to run that chilled water through a copper coil mounted on my intake fan. It acted more like a chilled-water loop. It definitely didn't have the "hit" of the direct expansion air, but it felt more consistent and handled the condensation much better since I coud just drain the main reservoir once a day. It pulled about 140 watts at the wall, which was a bit much for the cooling output, but it was a fun experiment in liquid cooling.

The thermodynamic efficiency of those R134a or R600a micro-compressors is inherently limited by the extremely small displacement, yet I suspect your BTU estimation might actually be slightly optimistic given the suboptimal laminar flow typically achieved across such a rudimentary evaporator configuration. I’ve found that shroud geometry is far more critical than raw CFM; if you aren't sealing the fan housing to the coil face with closed-cell EPDM foam, you're likely suffering from significant bypass air wich effectively dilutes your discharge temperature and ruins your sensible cooling capacity.

You're gonna wanna watch out for the vibration on your desk. Those ice maker compressors aren't exactly balanced for sitting right next to a monitor. I did something like this with an old wine cooler unit once and the buzzing drove me nuts after an hour. I'd grab some cheap rubber feet or even a piece of packing foam to stick under the base. It'll save your sanity if you're tryin' to focus. Also, don't be shocked if that compressor kicks the bucket early. They aren't really meant for 100% duty cycles like you're probably running. Most ice makers only run 'em for 10-15 minutes at a time.

Quick update—I threw some thick rubber feet on the base like suggested, and it realy killed the vibration. But man, the heat coming off the back is still a huge issue. It’s pretty much canceling out the cooling unless I point it away. Do you think a small shroud on the condenser side woud help, or am I just fighting physics at this point?