You are able to purchase the solenoid activated thermostat style controller for these AC units.
https://www.amazon.ca/gp/product/B01...?ie=UTF8&psc=1
Airxcel 8330752
Terminal labeling
B-: 12v Ground. Required for solenoid activation. There is a plain white wire with the red and white wires coming from the furnace at the factory thermostat location which can be tied to this wire. Or any metal ground would work.
Y: Compressor/cooling
GH: Fan high lead
GL: Fan low lead
The freeze terminals go to an included sensor, I'm not exactly sure what it does but I installed it the same place where the factory one was, up in the plenum.