So I am getting ready to start building my walk in cooler. I have two of the smaller (probably 5000 btu) AC units that my brother is giving me for the project. They are older units so by using two I won't lose total cooling if one goes down and I want the temps down around 36F so I figure also with two units going they will have an easier time maintaining temps.
My question is that it seems the easiest solution as far as temp control is the either get the AC thermostats outside the cooler or put a light bulb or similiar heat source on them to trick the AC into running and use a Johnson or similiar temp controller to turn the AC off and on as needed.
It depends on the AC units. I have one with a manual thermostat and I was able to turn the adjustment screw enough to get down to 40F in my ferm chamber. This was very easy to do. The other option is to bypass the AC's thermostat wiring and wire your temp controller directly to it.
Not sure how old they are so no idea if they are digital or manual. Bypassing the thermostat wiring seemed a little more difficult than the tricking the thermostat on the AC. I have seen a couple of the wiring diagrams for what you suggest but I am electrically challenged so I am not so sure what I am reading?