How to achieve 52 degrees F

OK folks I see many of you use window AC units for fermentation and storage coolers. I am building a 12 x 16 brewery building with a heavily insulated 4 x 12 walk in fermentation chamber. The digital controlled window AC units I looked at can only be set down to 61 degrees. Are you guys using Ranco type controllers to get the window AC units to get the room down colder by running wide open with their tstat disabled or relocated into hotter air? What am I missing?

Have you seen this thread?
https://www.homebrewtalk.com/f51/my-latest-project-walk-cooler-11440/

I have an AC unit with a manual thermostat. I didn't have to bypass the internal thermostat, instead I moved the adjustment screw.

I've seen someone do it for an apple cooler using a coolbot. I didn't know it was called a coolbot at the time. I did know it looked expensive and impressive.

I think you could do your own 'coolbot' using a STC-1000. Maybe just wire up the cool contact to something that makes a bit of heat like a few watt resistor, then tape that to the temp sensor on the a/c unit. Presto, coolbot like action for maybe 1/10 the price.

eta ... but it would not have an countericing measures for the evaporator then. I suppose one could use a second STC-1000 to monitor the temp just in front of the evaporator so if it starts icing up to cut off the heat source to the a/c temp sensor. That still wouldn't be too bad pricewise.

Sweet! I missed that post! Thanks.

I think the only main thing to overcome is evaporator icing countermeasures (that is a Subaru term). It's much more likely to ice the lower the temp goes as condensation forms on the evaporator. That's really all the coolbot is working to prevent in making the a/c unit go lower than intended.