AC Temp output / How cold does it get?

I don't think so. The coldest temp. I've recorded from my home AC unit was about 52F to 54F.

Is their a way to modify the unit or adjust to the lowest possible temp?

I do not think that a window unit is designed to go below 60° but some will.

Better bet would be to fit a refrigeration unit for a truck trailer. I believe that one those would accommodate the temperature you wish to achieve.

Yeah, but that sounds pricey - any other options?

Dry ice

No kidding - remember the old ice cream / Popsicle carts of yester-year?

Basically a cooler with dry ice, on a trike and they would be in the hot sun all day,

Kept everything frozen solid.

I'm trying to build a low budget walk in cooler and would like to maintain about 40 - 50 deg F.

It actually only needs to be cold for a few weeks at a time so, maybe dry ice wouldn't be a bad idea...

Won't the dry ice displace oxygen though?

I would like to be able to be inside to butcher / process the game.

I have used a cheap garage sale refrigerator to "hang" a whole deer during early archery season. The only modification was removing the shelves--It handled the flies and temperature beautifully--the only hassle was having to remove the carcass to wipe it down during curing and it had to be quartered to fit.

I believe that you would be able to drop the temp to what you wanted by locating the thermostat and the control bulb for the thermal expansion valve away from the chiller or heat exchanger.--I will look into it--Chilling water is trickier because of the freezing point.--Gotta go for now!

There is no set output temperature, air conditioning units typically have a 15 to 20° temperature drop across the evaporater. So assuming you progressively cool the room down to 47° the air leaving the evaporater using a 15° drop would would be at or below 32° and you would quickly start building up ice on the evaporater. This problem could be resolved by installing a defrost thermostat to intermittently shut down the unit when ice is detected.

You have a second problem the unit would probably be short lived. Air conditioning units are not designed to operate at those temperatures, liquid slugging would likely be a problem, this problem could be resolved by purchasing a heat pump as they generally incorporate a accumulator to prevent liquid slugging. Unfortunately they are much more expensive than standard units.

I would recommend that you investigate alternative solutions. Units specifically designed for medium temperature applications have a lower temperature drop across the evaporater coil, and are constructed to prevent liquid slugging.

It would not be impossible to modify a standard window unit for your application, but unless you have access to scrap parts and are qualified to do the modifications yourself it would be impractical.

If it is to be a short-lived solution bypassing the units internal thermostat, and installing a defrost thermostat might make it possible to maintain a box temperature in the mid-to lower 40s. The fan of course would have to be locked on high-speed, and the box would have remained closed as much as practical to prevent humid air from entering the environment. And you would still probably end up with a very short lived unit.

Around here, there are plenty of used restaurant equipment stores. Check around your area, or on the web. Maybe you can find a chiller from a walk in cooler, like at the beer store.

also must have ceiling AND floor similarly insulated. A window A/C will surely 'freeze up solid unless you have a defrost timer.

Yes, the room is 100% insulated.

With a timer, is it possible to get down to at least 50 deg F with a standard window AC unit?