This project uses an ESP-01 to monitor the temperature of the freezer, fridge and garage. It has  3 modes of operation depending on the measured temperatures.

Mode 0 - Normal "stock" mode used during warmer month of the year.  Data is still logged to ThingSpeak.

Mode 1 - Freezer boost: During the colder months when the garage temperature drops, the compressor will not run as often as needed to keep the freezer at the proper temperature.  This is due to the fact that the thermostat for most fridge/freezers is located in the fridge compartment.  When the freezer gets too warm but the fridge thermostat is still satisfied, the device will turn on the fridge light to add a little heat until the fridge thermostat activates turning on the compressor.  The light will stay on until the freezer cools to a predefined set point.

Mode 2 - Fridge boost: During severe cold periods where the garage temperature is below freezing, it may become necessary to add heat to the fridge to keep items from freezing.  This mode will raise the temperature of the fridge slightly without warming it enough to turn on the compressor.  This is accomplished by turning on the fridge light for only a short period of time.

Code is available on

Data/graphs of temperature probes.