I am HVAC certified and wanted to throw out a couple of ideas that I have.
- In my opinion the number one reason for Freon leaks in the system is either a failure of the blower motor or condenser fan motor. In which case create ice to build up on the a coil and creates stress and ends up shifting things around and creating leaks in the a coil.
My idea is to put a air pressure sensor above the furnace to indicate if a blower motor has failed and one also at the condenser fan. The one at the condenser fan I haven’t quite figured out yet in my mind.
You could use window sensors attached to the pressure sensors and then use rule machine. You could have the status of the sensors checked 3 minutes after startup and from there on out. If something fails you could have the system shutdown and then notify you.
- Another situation that causes ice up is low freon. In that situation you could use https://www.amazon.com/dp/B00QQNG3HY/ref=cm_sw_r_other_awd_JW.exbCQ499P1 and https://www.amazon.com/dp/B00IYE4X70/ref=cm_sw_r_other_awd_NX.exbKA1N5KV attach the sensor to the low side line set which is the fat one. Then you couldn’t get a baseline over time to what the temperature should be. And then if it drops below a certain degree it will shut down and notify. And of course also using rule machine again.