I'm volunteering for a food bank and trying to set up a cold room to store produce and other perishables. The main cooling will be done by a pair of air conditioners controlled by a Coolbot which enables the air conditioners to cool the room down below the usual lower limit for air conditioners (around 16 C). Neat device and they have a website with lots of useful information for this application. https://www.storeitcold.com/build-it/
In the winter, when the outside temperature is below the desired cold room temperature (around 5C), we'd like to blow the cold outside air into the room and exhaust the warmer room air out to reduce the load on the air conditioners. I need a controller with 2 temperature probes, one inside and one outside that will turn the fans on when the outside temperature is below 5 C and the inside temperature is above 5 C. Any suggestions?