The manually controlled Air Distribution Box # FACT11MA-PS does not include a freeze sensor or a way to add this type of sensor. You would need to install a Controller # FACC12SA-BL which communicates with a Thermostat # FR33PR to have a freeze sensor.
As long as you are cleaning the coils on your rooftop air conditioner, cleaning the air filter and not running the AC on max cool for long periods of time this should help to reduce the coil from freezing. view full answer...